Transmission Brace

I do not have any braces on my 360 with 904, he's on crack. I abuse the hell outta my car and I haven't broke any cases. I would do away with the stock rubber trans mount and make sure the driveshaft isn't to long. If the shaft is to long, when you hammer the gas and the rear end rotates forward and up it could be trying to shove the drive shaft thru the transmission. Lastly, it is very possible that the 340 you have is making some serious horse power and a 904 or variant of isn't going to survive behind it, but I find that less than likely unless you have made some serious improvements to the engine, if you left it in basicly stock trim I would say you are not making much more power than my non stock 360. I would definatly look at the other things i pointed out.