If I haven't forgotten, 81 through 86 blocks had 7/16" head bolts. The 86 blocks also appeared in early 87 models. Pre-81, 88,89,and 90 models had 1/2" bolts.
Thank you very much, because I have an 84 and 87 and they both have 7/16" bolts but some suppliers list different gasket numbers for them . I have been told it was because of a change in water ports, I always thought it was due to bolt size.
