Trinity Kinwald Dirtinator Motor

[JBL]

Whilst sorting out my old race gear I found the above motor. The motor seems in good condition and has probably only had one skim in its life. Can anyone tell me when these were produced? The motor can looks like a Trinity D2 and the box stats it is a 13X3. The armature looks as if it is handwound.I may try this at Stotfold on Sunday, just to find out how competative it is!