I had the welded on frame connectors installed a a couple of months ago and they are 100% what you all had noted would do for the car. Very nice. Once in a while I hear a sound that sounds like a left rear spring popping or maybe a shock on that side making noise. Could the rear springs or shocks need replacing being as the frame connectors were added making a them work differently/better? Rust free car but I thought about the control arm bolts and after getting a 3.23 rear from a rust free car I see that bolts were 3/4 rusted and thought maybe there could be some slop in the existing bolts as these were not replaced.
Thoughts guys. I did see the post of the rear popping noise another guy had in his and it was good reading.

 

I found that the left rear spring is rubbing on the differential mount per the fresh marks it left. A little oil fixed that. Most likely now that the SFC are installed the springs are working like they should.

 

... try rapping the end of the coil with some 3/4" heater hose, it will get rid of the squeaks/ popping noises