S&P adapters may/may not work w/o mods. There was a guy on PT that is going thru a swap into a 90's truck. He had to mod the S&P plates cuz it pushed the 5.3L too close to the firewall. They should work w/o mods if you flip the plates around. The reason for doing this is hole-placement for the OBS motor mount brackets.

I just dropped my 5.3L in my '86 Silverado this past week, and the BRP plates worked a lot smoother. PM me, and I'll send you the BRP URL. These plates were about $100. Bill Brewer owns the place. Or... you could check eBay for LS6 conversion plates.

The thing about using conversion plates is you may/may not end up working the motor in to get the proper "line-up" b/t mounts and brackets where the long bolt slides in. **NOTE: Engine lifts (or cherry-pickers) come in real handy for this.

Check the thread on this forum entitled "5.3L (LM7) Into OBS Silverado". I have pics there. BTW, wherever you get brackets from, make sure they're steel, not aluminum!

-Ron