Im currently using A factory team tc3 and looking to upgrade from brushed to brushless esc and 10.5 motor Just wondering before I blow a small fortune does anybody think I will have problems with diffs etc because of the increased tourque/power, as you know it is a very old car. Thanks in advance.

As long as your diffs aren't slipping and in decent shape you shouldn't have any problems. Before I ran a 5.5 in mine with no issues what so ever.

Upgrade the front outdrives to steel and be sure to shim any excessive play from the bevel and input gear and you will be fine. The TC3 was a very dominant car in it's day.