OK Jim
Here we go..... I'm only going to suggest things we did when we were racing against the A/P and B/P cars ... like you I didn't have all of the money, so I had to figure out how to do modifications on my own .... As luck would have it, we learned a lot and had much more confidence in the car when we got on the track. It is a great feeling when you win and have built or modified the vehicle you are driving.
Since you showed the Rear End.... here's some photo's of what you may want to consider ....
One of the problems we encountered was filling up our catch can on the rear end .... and we found out that the
oil was going out the breather or vent hose into the catch can .... and then would not return to the diff.... then we would damage the differential.....
These are the mods we did to fix that issue...
These are the things we did to KMP259 as well and it has proven very successful.