How come you need diff spring? Is your Slash the Ultimate version with bigger GTR shocks? (13 or 14mm, vs 12 for regular one) Don't use those progressive springs ..
If the motor wire is not "rubber" wrapped .. and model number with "R" .. 3355R 3351R.
Esc is easy to tell, can see 3 big capacitors .. But since Traxxas doesn't want to promote their "new 4 pole" system yet, and they still hv lots of 2 pole inventory.
For sure 4pole motor will fit a 6lbs + 4wd better, but I worry about the esc, seems same spec as old one, which have issue to run 3s, now new 4 pole motor will draw even more power... wonder how the new esc does.