could go either way, depends if it's a r30 or a k3500. I think a K3500 will be IFS. I have had a few R/V 30 1 tons, they were all Dana 60's with kingpins. That is the old body style, they ran up to 1991 in the 1 ton trucks R/V series and Suburbans. But you could also get a k1500/2500/3500 from 88 and newer in the new body style.
a little confusing, i know.