I have done the same with the rear cover, where the studs aren't removable without separating the transaxle front and rear cases. Many do the acorn nut thing there too. I used a gear lube specific sealant. I think it's the green Permatex stuff that has a funny smell to it, not the regular RTV sealant smell.
PANTERA INTERNATIONAL
A DE TOMASO CAR CLUB
Presents the De Tomaso Forums
The On-Line Meeting Place for De Tomaso Owners and Enthusiasts From Around the World
Clicking on the banner will take you to the sponsor's website.