I swapped out my open 3.88 for a 4.22 LSD
in my case i put a complete 2nd gen diff in a first gen truck, there was no issues.
What tyre size are you running as this makes a difference, (my truck went from 14's to the biggest 15s i could fit and not foul the front arches)

you need to plug your final gear ratio (probably overdirve?) current diff ratio, and tyre size into a rpm calculator and then go from there


Theres a few different options depending on what you end up with, the trucks had a few different diff ratios, you have the option to swap in a diff from a few other vechicles or to buy the diff gears seperately



Power wise
my truck has no issues with the open diff or the LSD with 170hp.
The guy i got my diff off had his v6 twin turbo'ed and if i recall correctly the open diffs last a bit longer when you rag on them, theres a pin that shears off and wrecks them. but if you drive sensibly you can use the original no worries. If the one thats in there is of a suitable ratio even better as its free