Auto Trans swap in 72 GMC - Need Help

[scorpion1110]

Gentlemen, I need your sage advice. I am getting my mind poisoned by the local truck guys. I am here in search of one or two gurus who can keep me on the straight and narrow.

So three weeks ago I buy a 1972 GMC Sierra Grande. My wife doesnt say a word because she knows that I am dealing with some serious health issues (the kind that involve biopsys and make me ensure my beneficiaries are current on all accounts). She thought the GMC would be good medicine and I love it.

Its a 3500 Camper special, 8 1/2 foot bed, factory tach, blue houndstooth, auxilary gas tank and electric fuel pump, wood bed and 4:11 posi. A nice solid old GMC. AND its a 4speed. Well I generally like rowing gears, but I find the 4 speed kind of annoying. I start it in second, but try and downshift well arggh. So i decide that the truck might just be a better driver as an automatic. I will run 31" tires and hopefully just driving local, revs wont be an issue and if it does go on the high way I will just deal with it.

The Plan is a conversion with a TH350. I know I need flexplate, shift linkage, column with shifter, trans, convertor and a drive shaft that accomodates the auto and an auto crossmember.

So I call a trans guy who tells me I need a TH400 and that I will blow up a Th 350, then a friend says a 700r4. Another says that a Muncie might be a fun swap (and I can build one thats tough) but I am not sure anymore how to go.

Now all I want is a TH350 and a truck that is a bitt easier on me to drive.

So Gurus, HELP!

1) can I run a TH 350?
2) if I built a Muncie M20, with bigger bearings and a cast iron midplate would it stand up to the truck.
3) if the Muncie and the TH350 are deal breakers than must it be a Th 400 or should it be a 700R4.

And finally I am talking to some folks in MD who have some of the parts, but if there was a guy with a rolling frame in the area that was set up as an auto, I would show up this weekend with Cash and take it (Hint Hint).

Thanks guys (and gals) for reading- I appreciate your help

S