the 12 bolt is slightly stronger than a gm 10 bolt so with a v8 its good for up to 36" tires with a locker. the dana 44 front (might have been a gm 10 bolt front, looks very similar) is good for 35" tires with a v8. not the best axles, but they're very common and the front axle can be upgraded to about the same strength as a dana 60 for less than a dana 60 would cost.
if you dont like the carb and the body style of the older truck stick with your 87. those axles under that truck are cheap, 100 bucks hub-hub is about average.
