nbrs on the outside of the frame were usually part nbrs. there should be a # also on the other rail which may be one digit difference.
a chev frame will have tge ser # embedded on the top of the frame by the steering box which should corespond to which is on the Vin plate; just the last 5 or 6 digits. GMC will not have it on the frame. tnere is not much difference between a chev and gmc frame once someone puts a xbc in it. the exception is the rear suspension. GMC have semi- elliptic springs and Chev have coils, there has been a lot of juggling around with bodies and vin plates over the years ansd most do not seem to care of the legal part of it. the onus will always fall on you if something goes cow poop.
if you are ever in a serious accident with it and no one is ever invincible. that is when things get inspected thourougly and things don't match you may have to have pretty deep pockets as insurance companies always like a way out out and if registration is not correct their gone.
the old story: it will never happen to me. accidents are always happening to someone
ron
