Hello all -
I am new here. I am considering a 4 speed conversion on a '68 firebird. I could use some help in getting the right unit and also would love to hear of any general advice on how to best get this done. My biggest concern right now is the rear-end has pretty dead gears with a 2:51 ratio.

I have access to a muncie m22 which I am told is a bullet proof unit, but I am pretty sure the rear end won't work well with the m22 lower first gear.

So let me know what you all think. Any advice or suggestions would be appreciated.

FB

 

The M20 & M21 are very strong too. They were standard behind many big blocks. Your best bet if you are set on a Muncie would be to find an M20. It has a better first gear. The 21 and 22 have the same ratios and will make your car a dog. You'd be better off looking for a ST10 if you plan on keeping those gears, you'll have a better choice of a deeper first gear.