[dpoltzer]

Hello, this is my first ownership of a 1st gen FB but have had many 2nd gens. My 1969 V-8 has what I believe to be the original rear end assembly in it. It has a 10 bolt cover and 2.79 gears in it. I want to upgrade from this open diff to a posi with 3.36 gears. Can this be done with this unit or do I need to go another route? Thanks, Dave

[mysticmissle]

i THINK, an aftermarket auburn case you can get down to 341s, only way to get to 336s is with a factory 2 series posi unit. i think you can go 273-336s with a gm 2 series posi unit
if you are interested in an auburn unit and 341s i have a brand new kit. i was going to use this to convert my 323 open rear, until i found a complete rear with 336 posi ironically enough

[Fourthirteen]

I believe that you can install any gear that you want as long as you buy the correct carrier (differential) for it. Check out the Auburn Gear website to determine which one you need.

[north]

Aftermarket replacement limited slip units and gear sets are limited to the 3.36 and numerically up range

[dpoltzer]

So I can call Summit or Jeggs and order the posi differential and the 3:36 ring and pinion?

[AG]

Yes, you can get a set of 3.36 or 3.55 gears and an Eaton posi or Auburn cone type. The Eaton is much better having installed them both.

[dpoltzer]

Thanks much AG.

[gtobird]

I had a really clean 68 peg leg rearend as a spare that I shortened by an inch on each side and installed the eaton posi with Yukon version of the 3:36 gears. If I remember correctly, even though they call it a 3:36 gear set, the ratio is closer to 3:42. When I called them to ask about it they pretty much thought it was a waste of time to bring it to their attention because the difference was so small. I suppose it's true as it's less than 2%, but wanted to make you aware of it. Not sure if other brands are the same or not. Also, if you've never done a carrier / gear swap, you'll want to buy bearings and shims. I bought a kit from one of the big name Auto Parts stores with Timken bearings for the 8.2 rearend that included gasket, seal, shims, etc. The problem was that the shim diameter in the kit was wrong. I then ordered a Yukon shim kit off Amazon and they too were wrong. After calling Yukon, they sent me the right size shims, no questions asked.

If you've never done this before, it's kind of a painful process getting everything spaced properly. I plan on doing it again on my wagon, but the first time around is a real learning experience and you need the tools to do it. You might want to check out YouTube for videos before you dive in.

OJ

Originally Posted by AG

Yes, you can get a set of 3.36 or 3.55 gears and an Eaton posi or Auburn cone type. The Eaton is much better having installed them both.

[gtobird]

BTW, when I say I called Yukon, it was actually Randy's Ring and Pinion who (I think) owned the Brand at the time. Not sure if they still do.

Originally Posted by gtobird

I had a really clean 68 peg leg rearend as a spare that I shortened by an inch on each side and installed the eaton posi with Yukon version of the 3:36 gears. If I remember correctly, even though they call it a 3:36 gear set, the ratio is closer to 3:42. When I called them to ask about it they pretty much thought it was a waste of time to bring it to their attention because the difference was so small. I suppose it's true as it's less than 2%, but wanted to make you aware of it. Not sure if other brands are the same or not. Also, if you've never done a carrier / gear swap, you'll want to buy bearings and shims. I bought a kit from one of the big name Auto Parts stores with Timken bearings for the 8.2 rearend that included gasket, seal, shims, etc. The problem was that the shim diameter in the kit was wrong. I then ordered a Yukon shim kit off Amazon and they too were wrong. After calling Yukon, they sent me the right size shims, no questions asked.

If you've never done this before, it's kind of a painful process getting everything spaced properly. I plan on doing it again on my wagon, but the first time around is a real learning experience and you need the tools to do it. You might want to check out YouTube for videos before you dive in.

OJ