[Your41Plague12]

Here's a post from Rich Weyand over at FSC that might help you out. I'd go with the 205 if you have a choice.

Originally Posted by rich weyand

Both are cast iron. Both are heavy. Both are hard to break. NP205 is gear-driven, NP203 is chain-driven. NP205 is part-time only (2WD or 4WD locked, HI or LO range), NP203 stock is full-time (4WD unlocked (differential) or 4WD locked, HI or LO range), but many/most NP203s have been modded to defeat the differential action; a modded NP203 is also 2WD or 4WD locked, HI or LO range. When an NP203 has been modded, it can suffer oil starvation at the output shaft bearings because the chain feeds the oil galleries, so with a modded NP203 you should drive the first mile with 4WD selected (with hubs unlocked), then shift back to 2WD, which you can do on the fly. If the hubs are locked, there is no need as the front wheels will spin the chain for you.

Either is fine. Take the easy path. If you have to do mods to accommodate the NP205, just leave the NP203 and swap the tranny. If you can swap the whole thing without a lot of screwing around, that's fine as well.

Much more on NP203 vs. NP205 via search. Here's one: http://www.fullsizechevy.com/forum/a.../t-458014.html

Either will work just fine.

Rich