I think a first timer can do this. Just take your time, read the directions and get your self a shop manual.

Check out the tech tip section here, there is a pretty good write up about the procedures regarding the 3:55 gear swap.

And for some nice photos of the step by step check out Sweet's webshots page which also shows some great photos of the bearings and bushings;

http://entertainment.webshots.com/album/554887855oSaqDX

~ Phillip
1949 GMC Suburban - 10 year project
1952 Pontiac Chieftain Convertible straight 8 hydramatic
1945 GMC half ton truck - Driver- Sold 9-15-25
1946 Chevy COE - SOLD 1-5-26 BUH BYE CHEVY!
1959 GMC Half ton long bed NAPCO