The class that allows blocks and weights is probably a 2.8 class. It will be hard to be competitve in that class with a near stock truck that has just a few freebee mods, and a chip. But then again I could be wrong and it be a 2.5 class. Anyway, that stock auto probably isn't going to last too long. Pull in the low side of the T-Case and shift to 2nd gear. That will probably be all the gear you can pull with. You can maybe able to look into a torque converter lock up switch and turn it on after you wind out 2nd gear going down the track. Also with it having a leaf spring front suspension, you probably will want to make a front traction bar as well coming off the top of the axle tubes, and then going back to the frame. With out that you may experience some major hopping down the track. I have see some use a wide towing strap hooking it to the leaf springs right behind the axle tubes and then too the frame to reduce hop.