While I have not ever tried to work on a TAC50-04 with only the OST, I don’t think it’s a good idea. Looking through the manual it does seem to have a lot of functionality but I think the Commands menu is a deal breaker. I don’t see a TBS but more importantly SFR or TFR and if you have to diagnose or replace a CAN node I see no CAN commands. And just in case you’re not aware, not all TAC50-04s came with an OST.