Two major things to verify prior to purchase (and insist that they warranty that those are indeed correct).
First and of primary importance (but generally fixable if you get them to adjust the price down to have it done for you) is "have the capacitors been replaced and any damage from them leaking repaired". The leaky cap issue affects all Spectras and is an age thing, not a use thing (even if the radio has never been used and stored in the best of conditions). The original caps will leak and if the leakage remains on the boards will eat away the traces on that board. Even if the radio works 100% without any issues, if the original caps (or caps the same type as the originals) are in the machine, the radio's a ticking time bomb and you either have replaced caps or caps that are leaking and causing damage to it. See this for more details -->
Recapping the Spectra
Second, make sure that the radio you purchase covers the frequency range you need it to cover. For the most part, the VHF models should be OK, although you may have some issues the lower you go on the 2 meter ham band. The UHF models may or may not work depending on which "split" your radio is. It may not work at all on the ham bands (well, without serious modifications), may work on the low side, but not the high side, work on the high side but not the low side, or cover the entire range as is. This has some details on the various splits for the Spectra -->
How to determine the range or split of your Spectra Radio
VHF Splits:
* 136-162 MHz (the one you want!!!)
* 146-174 MHz (may have issues below 146 MHz)
UHF Splits:
* 403-433 MHz (may not cover the top portion of the 70cm band)
* 438-470 MHz (the one you want)
* 450-482 MHz (may not cover the bottom portion of the 70cm band)
* 482-512 MHz (pretty much useless for 70cm use)
Be aware that the only real way to be sure of which split you have is to read the radio using the RSS software and see what it tells you. The model numbers are identical and will not indicate which split the radio is (talking the Spectra here, the Astro Spectra may indicate the split in the model number, but this would be what the radio came from the factory from, not necessarily what you will be receiving.
Decoding the Spectra model numbers -->
Motorola Spectra Models
Decoding the Astro Spectra model numbers -->
Astro Mobiles