Wrong Timing Chain Tensioner???

[Bicykiller]

I have an 82 300D turbo and had the chain tensioner fail. Upon removal and ordering of the replacement, I've noticed they are quite different. The new one is apparently the proper one for turbos only, however, I don't have the end cap for it and it is no longer available to purchase AND I can't find it anywhere!
I have the tensioner, spring and gasket... just no cap!
So that's why I assume the PO put this one in because the full assemblies are readily available. Can I continue to use this type of tensioner???
I just need that damn end cap! It's listed as a 19mm bolt in the haynes book...