GM did offer IFS on 1.5 ton trucks much later than 72. Many P30 chassis came with IFS and a similar 5 and 10 lug bolt pattern to what you may already have?
They made these in the 80's for sure, probably even the 90's, and later??
This Tech Tip is geared toward I-beam axles, but there is a very little bit about the different P30 and similar chassis with IFS.
http://www.stovebolt.com/techtips/bigbolts/p30swap/Personally I would stick with the I-beam, In my opinion they ride just fine for a truck.
Grigg
