I love my 77 CJ5, but i dont much care for the 3 speed trans, im used to my 1 ton diesels with 6 speeds or 5 speeds, or my fiancee's 08 JK rubicon with the 6 speed. I would love a 5 speed so id have more gear options. Im planning on lowering the gears to make up for the 33's, but with only 3 gears i dont wanna lose the top end, cause i drive my jeep to and from the farm most of the week so i can leave the dually at home, with diesel at 4 bucks a gallon. My freind had the 5 speed behind the inline six in his cj7, and i was wonderin if one like that would bolt up to my 304? What are the easiest choices i got? Are there any bolt in 5 speeds or is this gonna have to be difficult and require custom stuff?  

I swapped a T150 with a T18 behind my 304 in my 79 cj7.  Top speed on the interstate is not more than 60, unless you ok really winding it up - which I'm not.  I just don't plan on getting anywhere fast.  But, that being said, the T18 is an awesome 4-speed transmission.  Granny low (1st gear) will pretty much idle over any obstacle in our path.  A good description of this tranny is, it's like a T150 with a Granny Low 1 st gear.  2nd, 3rd and 4th are similar to 1st 2nd and 3rd of the T150.  As for fitting right up, T18's were an option in 79 and I think in 77 also.  So the bell housing and everything bolted right up. I did have to fabricate spacers to lower the cross member/skid plate and I did have to modify the driveshaft lengths.  

Good luck.