Product review (5 stars): Works for Jenn-Air PRG4810 (Broiler)
I've been putting off fixing my broiler for 5 years now because the part was so expensive when I could find it and I thought I'd have to pull out the oven to replace.  I finally decided it was time and suddenly couldn't find the part anywhere by searching for my specific make and model.  The bake igniter (replaced as well) is much easier to find, and here on Amazon is a good price.  So when I bought the bake igniter, I took a chance on this part by basically eyeballing the picture since the listing doesn't have accurate dimensions and I'm happy to say it seems to be exactly what I needed for my Jenn-Air PRG4810.  The heating element is 2" and the ceramic body is 5 1/4", exactly like the part it replaced (whether this was the igniter that originally came with my oven, I don't know).

I'm even happier to say I didn't have to pull the oven away to replace the part.  I found that you take off the convection fan at the back of the oven (8 total screws) and this leaves an opening to get to the porcelain wire nuts, although it's a tight squeeze.  You have to be very careful not to drop the wires or they'll fall behind and you'll probably go crazy trying to fish them out.  I cut the wires away from the old part and carefully fed them around to the opening, which gave me some length to work with.

One other note of caution, the heating element is brittle so be very careful with it.  Once I cut the wires on the old part, I was able to remove it from the oven, take off the metal shielding unit and put it on the new part.  This provides a bit of protection, but even so I was very careful with it.  I found that once I fed the wires through the opening, I was able to screw it back in completely and then finish wiring it up without worrying that I was going to bump it and have it shatter.

And like magic once I put everything back together and turned the power back on, I had a working broiler for the first time since I moved in to my house.