Ok. I was wondering since you said they were 16.5s in your first post. GM stopped using 16.5s in the early '80s. What you have are most likely 17s, which what they have on the newer trucks. Those won't work on the older trucks very well. An adapter/spacer is the only way they'll work, and many tire shops will not touch a vehicle with those installed due to liabilities. Best bet would be to get wheels with the correct backspace/offset, which will be less likely to cause bearing/scrub radius issues, plus it's 8 less lugs per wheel to make sure are torqued properly.
