I see the old style 73-87 wheels on the ifs trucks 88-??.  Is it possible to do this and retain the alignment/caster/camber?  Does the difference is backspacing/offset cause the steering geometry to be bad to the extent that tire wear is out of control?  

The only difference in the wheels is the size of the hole in the center.  The older wheels have a larger hole to fit over the hubs, which stick out on the older trucks.  The newer trucks with I.F.S. (Independent Front Suspension, 1988 and up) dont require these large holes due to their design.  

The old wheels should fit right on the newer truck with no issues at all.  However, if you try to put the newer wheels on the older truck they will NOT fit because the center hole is too small.

Hope this answers your question,

Randy  

and make sure the size is corect (15"-16") cause ive seen sometimes that one wheel will fit on newer truck when one wheel wont because of bigger brake issues...even on 16" the back brakes may be bigger.  

Thanks for the info.  I'm trying to fix up a 91 and the wheels are kind of trashed.  So I'm checking my options.