Pressure Protection valves

[miacasa_2000]

I have a 2003 Dynasty   I have both valves on the front tank leaking at the seams. don't want to mess with taking them apart to fix gas gasket I feel safer with new ones and only want to do this once.

Question 1. Has anyone done this  are there any pitfalls I should be aware of and did you also replace the fittings or reuse your originals? I guess that's actually 3 questions.

On my research of the valves seams the original opens at 65psi and closes at either 45 or 55 psi. The new direct replacement from Haldex opens at 70 and closes at 65 psi. I'm of the opinion that that doesn't matter much new one just keeps more air in the tanks for the brakes should there be a catastrophic failure in suspension/accessory system.    Question 2. Do you agree.

Also some are now plastic bodies vs metal they say for corrosion but I wonder about plastic getting brittle and cracking anyway. Question 3 Any thoughts or are yours plastic?  

FYI  original is Wabco N15759DC  crossed to Haldex KN31000  which is now 90555396 I couldn't find a new Wabco#  I did find some brands I never heard of.

Thanks in advance  Roy