Is anyone familiar with the kenwood tm-431a for the gmrs band . Thought I might ask before I bought it off another website?
That -is- a 70cm amateur radio and does not have type certification. It cannot be legally be used to transmit anywhere outside the amateur radio bands.
Bone stock, it won't allow you to transmit anywhere outside the 70cm band. If someone is selling it as a GMRS radio, they've opened it up and made modifications to make it work outside the band.
Legal issues aside, often, the radios have filtering in them designed to reduce out of band emissions on the TX side. That can reduce power output when used far outside the intended frequency range.
There are better, cheaper, legal options than hacked amateur radio gear.