1986 Heavy Duty 3/4 ton 454 Question?

[larryboz]

What year did the 454 go to 1 piece rear main seal? I think mine on my 86 is a 2 piece and it is leaking. Just picked up truck 2 wheel drive brand new BFG all Terrains 454 runs good carb needs rebuilt, hard cold start Turbo 400, 14 bolt Full floater 4.10 rear end, rusted out rockers and cab corners. What would you guys pay for something like this here is the pic I have of it

http://www.castleboz.com/photos/1986-Chevy-3-4-Ton