gm differential fill plug size

[mik2]

What is the size/type of fill plug on rear differential chevy express 2500? I think mine is aftermarket magnetic type with 3/8 extension slot. The oem looks like an oil drain plug but is 30 bucks! I dont see a size listed.

I was hoping to use a new oil drain plug or a npt black iron plug. Will any plug do in this application?

 

[clinebarger]

1/2" NPT......Most GM rear differential fill plugs are 3/8" square drive.

 

[JayhawkRoy]

Rock Auto has an AC Delco OEM as inexpensive as $7.08, plus shipping. Take a look.

 

[mik2]

Thanks alot for the information, i may add one to my next rock auto order....

Any reason I cant use a 50 cent black iron npt plug?

 

[clinebarger]

I'd rather use brass as it seals better & little chance of it getting stuck in the future. They're usually 3/8" Allen drive.