What rear ratio do you have ? Your Richmond is 1:1 5th correct ?
It has the original factory 2.41 posi, which works REAL WELL with the 3.27 1st in the Richmond.
Yes, 5th is 1:1.
On the Interstate by itself, it is just great. But when pulling a trailer, I wish I had a lower rear gear.
I have a 76 2.73 12bolt (YES, that's right, a 76 12bolt) with 2.73 gears that has been out back for 6-7years just waiting for me to build it. Several years ago, one of my sons found a 2-series 12bolt posi unit for $25 at a swap meet. Looking in my Olds parts, it APPEARS that there were only about 3 gears available for this style rear: 3.08, 2.73, 2.56. The axles are huge, I think they are 32 spline. As best as I can determine from the Olds parts books, this rear was only in GM A-body wagons (Curlass, Lemans, etc) and some El Caminos. They were probably more common than many people realize because they have a 10-bolt rear cover with 2 big notches.
Some covers have a filler plug as well as one on the side of the cast iron center section.
These 73-76 12-bolt posi rears are an Eaton unit, but larger than the earlier 65-72 Eaton 12-bolt posi. They also use larger left hand thread bolts for the ring gear.
Freddie Byars (Big Gear Head) says he has never seen one.
By the way, thanks. I put a mid-60s alum Chevy distributor in the Sun dist machine and did all kinds of things with it and talked to Dave Ray. I kind of know how to use one now.
Also, It appears the condenser testing meter does now work in the capacitance testing mode.