Originally Posted by 80cj
M22's have a close ratio gearset with a 2.20 first gear. Not the best for a Jeep especially if you plan on running larger tires. It'll feel like you're trying to start off in 2nd gear.
I have to correct myself here. M22's are available with both the close ratio(2.20 first gear) and wide ratio (2.54) gear sets. 2.54 is still relatively high (numerically low) for a Jeep, though.
Edit: IMHO, a T-176/177 with a D300 would probably be better. Better ratios, built in top shifter, overall length probably shorter. T-176/177 strength comparable to Muncie. You would have to purchase an adapter plate to mate the T-176 to the Chevy bell housing unless you luck out and find an iron duke bell housing that was used with a T-176.