Short Pressure Relief Valve?

A buddy of mine got me a line on some super cheap ball locks... he found a cache of them sitting outside a barn since forever... so i bought a few of them.. . knew they would need some work and parts replaced, but couldn't beat the price, so i'm dealing with it.

but...

one of the lid pressure relief valves was corroding, so i took it apart to get a replacement... only to find that the replacement is way too big, and i need a short poppet... not the longer ones that are sold today.

been searching for a while with no luck... anyone know where i can find a short pressure relief valve poppet?

That looks like a type D found on older firestone kegs, although most of the ones I've seen had the tab instead of a ring. I thought both Williams Brewing and CHIcompany carried them, but apparently not, or at least not anymore. The picture for the relief valve page on the CHIcompany site shows one, but once you open the page it seems that they only carry two versions of the type A (same as your replacement that doesn't fit). You might have to replace the whole assembly with one of the dome type valves.

http://www.williamsbrewing.com/REPLACEMENT-DOME-TYPE-KEG-LID-VALVE-P3011C78.aspx