Morrie, There were mid sump and rear sump pans for the Nailhead - no deep sump pans unless you made one. The one Walt linked is a rear sump that fits the rear sump pan of the 65-66 GS Skylark. I bought one from Carmen a while back and I think it was about half the cost of that one. Just be careful of the flange and contact with the crank. Mine needed a little grinding there. You need to talk to Carmen if you have not yet. He is reasonable and knows his stuff, but is not on line - 716 693 4090.