We use to run with the spool on front, and it takes a little to get use to (tarmac) on carpet I would recommend to go back to diff F/R. Also, I would recommend to change the balls and pads in diffs to make sure that they were not damaged, it is fairly hard to see the damage just looking at them, they are cheap, so invest in these.
You have to move the batteries outward for Lipo, otherwise the weight is too much R/L, usually until you can connect the inside pack plug on the outside of the top deck.
The TC5 has a tendency to have the arse wanting to move to the front, it takes some time to set-up properly. Do not hesitate to put weights on the battery side either.