Proportioning Valve differences

[joeydurango]

Need a new prop valve for my '72 K10 (disc/drum). Found @ LMC, for $180: http://www.lmctruck.com/icatalog/CB/full.aspx?Page=166

And also at GMC Paul's, for $80: http://gmcpauls.com/Brakes&Steering.htm (second line)

Not wanting to forgo the $100 price difference, and would also prefer to give GMC Pauls the business. But these look different, and the LMC one looks stock. Don't care about the looks - just want to confirm with someone who might know better than I that the GMC Paul's one is a direct-replacement for stock. Does it look different just because it's a newly-made replacement part, or is something different that I'm missing? Not tons of info on GMCP's site. Thanks! The truck is inching closer to completion...