Muncie M-20 for '68 el Camino - Chevelle Tech
Transmission & Driveline Transmissions and Differentials

 
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post #1 of 8 (permalink) Old Oct 26th, 16, 5:28 PM Thread Starter
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Bruce
 
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Muncie M-20 for '68 el Camino

My '68 el Camino SS 396 has the correct factory motor (325) with VIN stamped on the pad and the correct 12 bolt rear, the Muncie trans in it is dated P7D067, which is too early for the COWL tag 12C build date, so not the original trans. Has the speedo output on the passenger side. Also VIN code stamp does not match.

I came across a Muncie trans (M20 - 2 grooves on input shaft) datedP7P30 which would work, only issue is the speedo output is on the driver side, the casting numbers are:
Main housing - 3885010
Tailshaft- 3846429
Side Cover - 3884685

Does not look like it has a VIN code stamped in it?

Would the '68 SS 396. 325 hp have the speedo output on the passenger or driver side? This one might be for an Olds or Pontiac?

Checked my Colvin, ChevelleStuff, no real help?

'68 el Camino SS 396/325hp, 4 Speed, 3.31, Buckets, AC
'72 el Camino SS 454 4 Speed, 3.73 Eaton LSD, Buckets, AC
'75 el Camino SS, 400 SB, 200R4, 3.42 LSD, AC, Swivel Buckets, PW, PDL
'87 el Camino SS 305 TPI, 200R4, 3.73 LSD
'87 Buick Grand National (Hardtop, Bucket Seats)
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post #2 of 8 (permalink) Old Oct 26th, 16, 8:01 PM
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Jeff
 
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Re: Muncie M-20 for '68 el Camino

Quote:
Originally Posted by PaceCarNut View Post
My '68 el Camino SS 396 has the correct factory motor (325) with VIN stamped on the pad and the correct 12 bolt rear, the Muncie trans in it is dated P7D067, which is too early for the COWL tag 12C build date, so not the original trans. Has the speedo output on the passenger side. Also VIN code stamp does not match.

I came across a Muncie trans (M20 - 2 grooves on input shaft) datedP7P30 which would work, only issue is the speedo output is on the driver side, the casting numbers are:
Main housing - 3885010
Tailshaft- 3846429
Side Cover - 3884685

Does not look like it has a VIN code stamped in it?

Would the '68 SS 396. 325 hp have the speedo output on the passenger or driver side? This one might be for an Olds or Pontiac?

Checked my Colvin, ChevelleStuff, no real help?


I believe 63-65 were driver speedo and 66-74 were all pass. speedo exit.

What's wrong with the Muncie in the car besides date codes?

Recheck your date code on your installed trans. D= April, 67th?

Jeff

64 El Camino Pro street, 496, T-400, 9" 3.73


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post #3 of 8 (permalink) Old Oct 26th, 16, 9:23 PM Thread Starter
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Bruce
 
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Re: Muncie M-20 for '68 el Camino

Quote:
Originally Posted by fr8dog View Post
I believe 63-65 were driver speedo and 66-74 were all pass. speedo exit.

What's wrong with the Muncie in the car besides date codes?

Recheck your date code on your installed trans. D= April, 67th?
Nothing wrong with it.

Date code is P7D03, typo on my part! :-(

Heard that possibly they carried over the speedo on the driver side beyond '65 into '68 with Old's & Pontiac's, any truth to that? ChevelleStuff showed the tailshaft number but no application?

'68 el Camino SS 396/325hp, 4 Speed, 3.31, Buckets, AC
'72 el Camino SS 454 4 Speed, 3.73 Eaton LSD, Buckets, AC
'75 el Camino SS, 400 SB, 200R4, 3.42 LSD, AC, Swivel Buckets, PW, PDL
'87 el Camino SS 305 TPI, 200R4, 3.73 LSD
'87 Buick Grand National (Hardtop, Bucket Seats)
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post #4 of 8 (permalink) Old Oct 26th, 16, 10:56 PM
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Jeff
 
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Re: Muncie M-20 for '68 el Camino

Quote:
Originally Posted by PaceCarNut View Post
Nothing wrong with it.

Date code is P7D03, typo on my part! :-(

Heard that possibly they carried over the speedo on the driver side beyond '65 into '68 with Old's & Pontiac's, any truth to that? ChevelleStuff showed the tailshaft number but no application?

I believe you are correct. Here's a link that states some Pontiacs got the driver side speedo up to about 1970:

muncie speedometer gear - ChevyTalk - FREE Restoration and Repair Help for your Chevrolet

Jeff

64 El Camino Pro street, 496, T-400, 9" 3.73


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post #5 of 8 (permalink) Old Oct 29th, 16, 11:51 AM
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Re: Muncie M-20 for '68 el Camino

The Muncie trans coded P7P30 was built Sept. 30th 1966 for 1967 model year... P7D03 was built April 3rd 1967...

Neither trans is correct for 1968 model year, but will fit in a 1968 Car just fine...

The driver side speedo tail housing was used in Pontiac A-body's thru the end of the 1970 model year...

Hope this helps... Crash
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post #6 of 8 (permalink) Old Oct 31st, 16, 12:53 AM
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Re: Muncie M-20 for '68 el Camino

Hi Bruce,
PM sent.

Hopefully this will help:

Muncie 4 Speed Transmissions and Parts

3846429 ~ 1963-1965 Regular thick web, driver speedo, 27 spline
Used up to 1970 in some Pontiac Models

Tory
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post #7 of 8 (permalink) Old Oct 31st, 16, 7:04 AM Thread Starter
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Bruce
 
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Re: Muncie M-20 for '68 el Camino

Quote:
Originally Posted by crashent View Post
The Muncie trans coded P7P30 was built Sept. 30th 1966 for 1967 model year... P7D03 was built April 3rd 1967...

Neither trans is correct for 1968 model year, but will fit in a 1968 Car just fine...

The driver side speedo tail housing was used in Pontiac A-body's thru the end of the 1970 model year...

Hope this helps... Crash
How do you get Sept 30, 1966 from P7P30? According to my Colvin book:

P: = Prefix - 4 Speed Muncie
7: Model Year = 1967
E: Month = September
30: Day of Month (September 30)

So are you saying that this is actually built on September 30, 1966 for a 1967 model? From the way I read it, that is built September 30, 1967, what I don't have on either of these trans is the main case casting dates that would clarify this.

End of the quandry on the trans I was looking at anyway, decided to pass on it since the tail housing having the speedo output on the drivers side, that's just not correct for my '68 el Camino.

:-)

'68 el Camino SS 396/325hp, 4 Speed, 3.31, Buckets, AC
'72 el Camino SS 454 4 Speed, 3.73 Eaton LSD, Buckets, AC
'75 el Camino SS, 400 SB, 200R4, 3.42 LSD, AC, Swivel Buckets, PW, PDL
'87 el Camino SS 305 TPI, 200R4, 3.73 LSD
'87 Buick Grand National (Hardtop, Bucket Seats)
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post #8 of 8 (permalink) Old Oct 31st, 16, 7:29 AM
Cam
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Cameron Milne
 
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Re: Muncie M-20 for '68 el Camino

Quote:
Originally Posted by PaceCarNut View Post
Nothing wrong with it.

Date code is P7D03, typo on my part! :-(

Heard that possibly they carried over the speedo on the driver side beyond '65 into '68 with Old's & Pontiac's, any truth to that? ChevelleStuff showed the tailshaft number but no application?
Quote:
Originally Posted by fr8dog View Post
I believe you are correct. Here's a link that states some Pontiacs got the driver side speedo up to about 1970:

muncie speedometer gear - ChevyTalk - FREE Restoration and Repair Help for your Chevrolet
Quote:
Originally Posted by crashent View Post
The Muncie trans coded P7P30 was built Sept. 30th 1966 for 1967 model year... P7D03 was built April 3rd 1967...

Neither trans is correct for 1968 model year, but will fit in a 1968 Car just fine...

The driver side speedo tail housing was used in Pontiac A-body's thru the end of the 1970 model year...

Hope this helps... Crash
I was very surprised to discover that in 1971-onward, on Pontiacs, the Warner Super T-10 replaced the Muncie M20 in cars like the Lemans. I would have expected the Warner to replace the Muncie around the 1975 model year (74 on Z28s) but my neighbor's untouched, 1-previous owner low mileage 72 Lemans GT 400 4-barrel with a factory 4-speed had a Super T-10. I also found a 1971 picture on the Pontiac assembly line that showed a 400 with a Borg-Warner trans. The HD close ratio 4-speed was still the Muncie M22 though, through 1972.

I had also heard that Oldsmobile ran the speedo off the front wheel, not the tailshaft around that time. One does tend to hear a lot of rumors though; Olds had front wheel drive on the Toronado so I wonder if that is where the rumor took shape.

"The more you know,
the more you realize there is that you don't know." - Dad


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