Hey a question:
I'm trying to decide what to do. I have a 70 SS with a fresh 454 (505 hp). I am using a 10 bolt 8.5" from a '73 or newer Monte. It has a 390 gear. I had to modify the upper control arms to fit the wider angle of the "ears" on the differential. The lower ones bolted up o.k. But not until I went to replace the lower trailing arms, (soft bushings) did I realize that they fit o.k only because the bushings are so mushy they will spread wider. I understand that certain 72 Monte's had the 8.5" 10 bolt and had the right mounts for my Chevelle, but I can't find anything for a reasonable price. The 12 bolts are out of sight here in Ohio!
Do I modify the lower trailing arms to make it fit, or keep trying and spend BIG bucks or what? Any input from you experienced guys will be appreciated! Thanks in advance!

tim

Tim, what are you going to do with your car? are you going to take it to the drag strip?or just drive it on the street?and is your car a 4 spd.or auto?

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Don Edmonds
T.C.Member 1033
1969 Chevelle
2000 Harley softail deuce
www.bottlerats69.homestead.com

Thanks for the response Don,

No strip, just a nice driver that once in awhile I "let loose" for a little exercise! It is an automatic, actually a professionally beefed up 350 Turbo HD.

Be safe and do a 12 bolt. There here in Ky for under 250$$ in the bargain Mart. Keep your eyes open you'll find one. Build it a bit and pretty much forget it.

Tim.you could get away with the 10 bolt.but if it were me. I would find me a 12 bolt.but before you go shopping.beware all 12 bolt are not created equal.when you go to buy one.pull the cover off and count the bolts on the ring gear.if it has 12 bolts you're good to go.if it has only 10.then take a pass on it.and if the person you buy it from says it's a posi unit. then spin one of the drums the other one should spin the same way.then have someone try to hold one drum while you try to spin the other.if you can spin it.then pass.or bargain for a better price cause the posi unit is bad.if you need any more help give me a shout.a good 12 bolt posi rear end should set you back no more than 600 bucks.but sometimes you can come across one for around 400 bucks.if red can find you one for 250 its more than likely an open carrier unit.(not a posi)but still a deal.you'll have to buy a posi carrier and a gear set.then have to find someone to set it up.so by the time you're done your still gonna have about 600 bucks in it.

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Don Edmonds
T.C.Member 1033
1969 Chevelle
2000 Harley softail deuce
www.bottlerats69.homestead.com

i forgot to tell you that when you have the cover off of a rear end.to figure out which gear it has. count the number of teeth on the pinion and the ring gears.then divide the number of teeth on the pinion. into the ring and it will tell you what gear you have.

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Don Edmonds
T.C.Member 1033
1969 Chevelle
2000 Harley softail deuce
www.bottlerats69.homestead.com

find an 8.5 from a 71-72 non-chevy A body(skylark, cutlass, lemans) it will have two square nubs on the bottom corners.
you're right, 12 bolts are ridiculously expensive now (i wish i could find one for $250) but an 8.5 is close in strength. plus it will bolt right in.

ps-you will need a spicer conversion u-joint...

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Rich Miller, 1970 Chevelle Malibu 350(soon to be a 468!)
1973 El Camino (wifes car)
My POS(it looks better now, i promise!) (http://www.geocities.com/richrachel_69101)

What size of tires are you running on the car and are you using a posi?

If your not using big tires, I would say any old 10 bolt will do. People will say a 10 bolt is only good to x number of HP, but the fact is they're only good to x number of horsepower being planted to the ground. On street tires I don't think i'd worry about it.

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Chris Dagenais
Saskatchewan
'71 Malibu with a home built 454!
"Hard work MAY pay of in the long run, but laziness pays off NOW"
My Page (http://www.ycworld.net)

If you can find an 8.5 10 bolt configured for 72 and earlier A bodies, you will have to be extremely lucky. I spent months looking for one and actually found more 12 bolts. A one legger with a 2:73 ratio gear will run $350 here.