I swapped 5.29 v6 gears into a 2wd 8" housing with no issues with the axles. However, I had to clearance the housing a bit though. The v6 gears are thicker than the standard 4cyl, so just grinding the notch in the lower part of the housing wider made it work for me.
Since then, the 3rd has been put into a housing from 86-up (don't know the actual year) with no problems with the axles. The only time you have to worry about it is if you have a 7.5" ring gear. But that would be a 2wd truck anyway.

Cliff notes version: swap away!

1986 Pickup extracab longbed "Woody edition"
SAS - 33's, 5.29's, lockright rear.

02 IS300 SportCross - my "DD"
94 2wd v6 extracab
04 Outback Wagon- wife's/family car