I got samples:

 3/8"BBB which are 27mm inside length...it's too short to work on the gypsy I have.

3/8" G4 HT which are 31mm inside length...it seems to fit OK.

The old chain is 30mm inside length, 10mm dia...so over a 12 link length it's 12mm shorter than the HT.

Does anyone know what my old chain is? (10mm dis, 30mm inside length)  If it's G3, of good quality, and available in the US, that's what I'd like to buy, as it's probably significantly cheaper than the HT.  I guess it may be some cheaper Chinese stuff which might explain the severe rust problem.  I don't know what to call it, so I don't know what to search for.

Thanks,

Kent