are the 6.0 and the 5.3 using the same block bolt pattern for the bellhousing?

 

NO, but can be adapted easily,. most important are the two locating dowels,GM alignment dowels to crank center line,depending on what trans. may have to get a adaptor plate, cheap from Summit or Jegs etc.

the 86 jag i looked at today used his 86 T400 adapted to the 6.0L, a 94 engine.

 

I found a running 6l im going to have shipped. One reason I wanted it was the crankfire ignition. Stroke the 6l crank 5.5mm and have it hardened get a stroke of 84mm.