i have an 80 cj5 with the iron duke motor and sr4 tranny, and im putting in a 350 and want to get an automatic tranny what will fit the best?  

the best fit is probably the th350 in length depending on what t-case and adapters get used,

the best tranny for the combo is the 700r4, 3.06 first, 1.63 2nd, 1. 3rd gear and .7 4th-OD will allow what seems a ridiculous low gear ratio. like 4:88/5:13
(4:88 figured) gears and 30" tires will turn about 2500 rpm @65mph, 34's about 2200 rpm @65, for a 350 sbc 2200 is a great cruise rpm for power and mileage. Ok now, thats my opinion.....the 700 is the same basic unit as a 350 without the overdrive. in a 4,000# jeep you'll not hurt a 700. (OD being the only weak link if it's used for towing)

BTW, the th350, 4:88's 34's @65 is just under 3150rpm.

want to see other ratio/tire size, tranny combo's?... I'll be happy to figure them.  

Hey Mudb8,
I've got a 95YJ that I blew the engine on. The tranny is stock and is in need of serious rebuilding. I'm thinking about a small block swap along with an automatic tranny so my kids can drive it on our property.
I've got 4:56 gears with a Detroit locker and Moser axle in the rear, all with a 4" Skyjacker lift. I'm gonna put 35's under it. I drive it to work every now and then. Any advice on a tranny and engine that'll be a good swap in, and what vehicle it would come out of?
Thanks