[LLLosingit]

My Son Inlaw has a stock 6.0/4l80e from a 2006 Chevy Express van and it had a 6-bolt converter/flexplate combo, His 3600 stall Yank converter was delivered today and it's a 3-bolt style and the holes don't line up, They are off by about a 1/4". I assume he'll need a different flexplate but not sure what is needed.
Is it feasible to die grind the hole slightly on the stock flexplate? He's on a tight budget and doesn't have the money right now for 2-3 hundred dollar flex plate.

Right now it's bone stock combo other than the 3600 stall converter.

 

[forcd02]

I have made the holes larger to fit-just make sure the snout pilots into the crank adapter.
Pull the FW and adapter off the engine, install on the conv, see what you have to do. Use
washers on the bolts. Is this ideal, no, but it works, lol. Main thing is you don't want a
bind, make sure the bolts have clearance.

 

[Hutch]

You have a converter that has the small bolt circle most likely. It would be best to drill the holes on a mill or send the converter back and have it made with the large bolt circle.


Hutch

 

[Circle-D]

Sounds like the converter has the LS bolt pattern of 11.066". The OE 4L80 flexplate is 11.5", thus your ~1/4" difference. Like mentioned above you can drill the flexplate, as Hutch mentioned they need to be accurate - preferable on a mill or with a centering jig. You could also get a used flexplate from a 4L60 or 6L80 vehicle and it will fix your problem, you just need to ditch the spacer between the crank and flexplate. Since the converter has the LS bolt pattern, I am assuming it has the longer pilot for the short LS crank.

Chris