Conceptually, this doesn't make a lot of sense, I suppose, but it's something I wanted to have a crack at. Sentinel Prime is based on GaoGaiGar RaiRyu (might not be a real one).
Naturally, he transforms into a big truck with lots of firepower. The base mode ladder and radar dish fold inside the cab/leg sections for the other modes. The main cannon, the two smaller guns and the radar dish are all on ball joints to allow them to train on targets over a wide range.