MT 500's with scan were slick radios in their day. In fact, the MT500 was one of the easiest radios to modify. My Fire Chief was a gadget guy. I built him an MT500 8 channel radio with scan, "Quik-Call", and multi-PL encode slaved to the channel selector. The scan switch was moved to the scan housing and the page reset switch was on the front cover.
Do you have a VHF or UHF radio? I still have a few dozen receive elements on public safety frequencies.
VHF MT 500’s were produced on 3 frequency splits: 136—150.8 (NUD-6241), 150.8 (NUD-6242), and 162—174 (NUD-6243). The info in parentheses correlates to the receiver board in the radio. If the radio was stripped of channel elements and the frequency label was missing from the rear cover, you could still determine which band split you had. That info was stamped on the inside of the receiver board.
As far as the scan function, it is not like a vintage crystal scanner where the lights scrolled across the lens. The scan LED would not light until the radio received a signal, then the LED would flash at the correct channel number on the escutcheon.
I never had the crystal manufacturer install the crystal. I did that myself. Cost for the crystal alone in the 1980’s was around $10.00. Compensating the element for the new freq was very easy.
As the others have mentioned, it will be quite expensive to get the radio up and running. For you, it would be a labor of love to have a rare vintage piece of working equipment from, in my opinion, Motorola’s better days.
If you can provide me with a list of the frequencies you need, I will see if I have them. They would be $25.00 each.
www.bomarcrystal.com
It looks like the cover of the element is soldered in place. I did not go any further. 
Probably should have just bought the whole assembly, but maybe it wasn't available or just too expensive.
