I know this is an older post, but let me share my experience with the PA military vehicle plate. First of all you have to have a 25-year-old vehicle. If it isn’t already registered as an antique (at least 25 years old) in Pennsylvania, you have to simultaneously register it as an antique and then also apply for the historical military vehicle plate. So, think of the historic military plate as a subcategory of antique plates in Pennsylvania. If it’s not an antique, you’re not going to get a historical military vehicle plate.
Because you have to get the antique registration anyhow, I recommend registering the vehicle as an antique and getting the antique plate. After you get your antique plate, you can drive your car around and then apply for a historical military vehicle plate. When that plate comes in, you retire the antique plate. The benefit of doing this is the antique plates in Pennsylvania are good for your lifetime. So since you’re paying the antique registration anyhow, you want to get that antique plate first and then you can keep it and put it on another antique car later on. Just be aware that it takes about three months to get an antique plate, so don’t wait till the last minute to get it registered.
I also recommend this “ antique first “ method because I waited six months to get my historical military vehicle plate. The problem was, when I did it in 2020, the instructions were not clear that the vehicle had to be registered as an antique first. It was a fiasco because PennDOT omitted that from the instructions on the form used to apply for the military plate. They have since corrected that. I am not sure how long it takes to get a historical military vehicle plate nowadays, but I bet it’s longer then the time required for a normal antique plate, because they’re rare and I think it depends on who is processing your application. Play it safe and get the normal antique plate first.
To give you an idea of how screwed up the program was, I got my military plate in the spring of 2021, after the program had been in place for three years. They were only up to number 32 in the sequence of plates. 32 plates in three years, in a state that has a lot of military vehicles in it. If you do a search on the G503 website forum, there was a guy there who went 18 months trying to get a plate. He ended up with plate number four. So the learning curve is getting better, but I wouldn’t bet on a speedy issuance of the plate.
Based on your post, your vehicle is not titled or registered in Pennsylvania. You cannot get a title in Pennsylvania from a bill of sale. You must have a title or a transferable registration from another state, to get a title in PA.
You can register your truck in New York State from a bill of sale if you have a weigh slip as well. Then you can transfer it to Pennsylvania from there. In New York State, you’ll have to get a title, because your HMMWV will be made after 1975.
Cars made in 1974 or earlier get a transferable registration in NY. I inherited a 1969 military vehicle from a friend in New York on a transferable registration, and had no problem getting it titled in PA as an antique. Because I already had an antique plate, I walked out the same day with my registration and could immediately begin driving the car. This fall, when I store the vehicle for the winter, I’ll apply for the historical military vehicle plate and should have it by spring.