What type and size is the bolt holding the old belt tensioner on a 1994 2.3 Ranger you can't see what type bolt there is it feels like a star or Allen wrench type?

The cap takes a T50, I am looking for the bolt size myself. My mechanic says it is probably metric, I would really like to know before I cut the head off to yank the old tensioner. If you know, please let me know.

An additional problem with this job is that the clearance is very tight, I tried to use a l-type torx wrench and a piece of pipe. The head of the bolt unfortunately was already stripped out so I am declaring war on the bolt. This agression will not stand.