i wanted to improve on the GM design.
5/8-11 jam nut welded over the fill hole
5/8-11 x 3/4" long stainless steel hex head bolt to replace the "rubber plug"
1/2-13 jam nut welded at the bottem of the cover
1/2-13 x 1/2 long stainless steel hex head bolt as a drain plug
then mounted to the Diff. using 5/16-18 x 3/4" long stainless steel heax head bolts.


Edit:well i was going to post a pic but it's too big.

 

lets try this

 

and this

 

looks good. i was planning on doing something similar this spring as well.

 

when i used to have my 9 bolt, it would always leak from the damn plug. good work.

 

nice job on the cover.
Mine has the plug removed with a fill bolt also. Additionally mine has a 1" spacer between the housing and the cover.
It adds addtional fluid capacity for cooling. This was done to car when it won it's class at Sebring, years ago.

I am going to add a drain plug to the bottom of the spacer to make it easier to serivce.

Steve