75 3/4 ton gmc sierra sm 465 bell housing

[seventy5GMC]

Hello
wondering if anyone can help, my bellhousing for my sm465 has 4 main boltholes to attach the tranny,Ive got the bellhousing bolted to an engine stand with the tranny attached. Theres a fifth threaded hole on the very top of the bellhousing which I cannot remember what bolts to it. this top hole sits above the trans so I'm guessing is part of the wiring harness bolted to this?
any help is appreciated.
thanks

[Captkaos]

You got a picture? 

[zieg85]

If the picture is what you have it is the newer dual pattern bell housing from a 81 on up

[seventy5GMC]

I have what is called GM #6263756,,,it has 5 holes,but my sm 465 has only 4,there's and extra hole at 12 oclock. its a through hole thats threaded, ??

[Captkaos]

That PN is for a 12" clutch/pressure plate for Trucks trans.  You don't need the 5th hole on the SM465.

[seventy5GMC]

thanks for the reply! is it best to fill the hole with a bolt anyway?

[Captkaos]

I would probably plug it.