What type of hinge is this & where to buy?

Sachse Rod Shop sells a hinge like that. Honda trunk hinges are similar and some minitruck hood hinges work like that but I would suggest the one from Sachse. Page 218 in their catalog. $75 a pair.

I thought I would also add... I welded to the bracing under the floor on the opening part. Behind the opening there are tabs that sandwich the hinge. I was able to tighten the bolts holding it together (using a nylon lock nut) just right so that the hatch would open and close good, but I didn't need a strut to hold it open or a latch to keep it closed. The tightness of the nuts and bolts held the weight. So there was nothing holding it up or down other than that.