This isn't really a axle swap and its not front end, but I have this old '78 2wd toyota of my dads that is junk but I'm gonna rip the rear end and tranny out of just for like a spare for my 88 toyota pickup. On the side of the 78 is a sticker that says 3/4 ton, so my question is, is the running gear in that pickup more heavy dutie than my 88? Which is rated for half ton, or are they just heavier leaf springs, or what?

 

I'm assuming the 78 2WD axle has 6 lug hubs(8" differential). If it does then it's probably relatively equal in strength to yours, and certainly not any more heavy duty than the 88 4WD rear. If it's got 5 lug hubs, then it may have a weaker 7.5" differential and weaker 27 spline axleshafts. If your 88 has a V6 then it has a stronger differential in the rear axle, but all the other components are comparable strength wise to the 8" 78 2WD axle. You do realize though that the widths aren't the same right? It's not going to fit on your 88 PU. The only thing that will be swappable to your 88 from it will be the 3rd member(IF it's an 8").