I have a group 75/86DT type battery in the car now, so I know a regular group 86 will fit. I'm probably going to do something like this at some point:
The thing is, that sure you can go to Pep Boys and maybe get a group 75/86DT battery, but the ones in my local store were like a year old. It's easier to get a more commonly available type 86 that is fresh and use it instead.