Lock a pretty good fit......well sourced!

 

They are available in 10 packs at Smoking Pipe Style Battery Terminal Insulating Covers Boots 10 PCS WS | eBay

Or if anyone wants some I have two extra pairs I can mail out. The material is tough in terms of taking stretching and pulling during install.

 

Discovered another exposed terminal that was staring me in the face but I had previously refused to see.

I recently lost a fan belt and was in the process of re-tightening the new one when it suddenly dawned on me that the socket extension I was using was hovering right over a nut on the alternator which held down a hefty cable running to the battery. Just blind luck I hadnt hit it yet doing the replacement or the follow up tweaking.

I'm glad I got the bulk pack of these covers, I keep finding uses for them