I have a great condition Warburton 11D with a T2 and T4 backbore. The 4 backbore is slightly different perhaps an older design but still in great shape.

It's a great 6 3/4 size piece with a more V shaped cup. I would compare it in size and blow to a Stork T1 lightweight. Make me an offer or trade for something in the 5 or 11 range.