Hi grumpy, it fits into the dog that is on the end (red shaft) of the 'counter -shaft' that would (I'd guess ) have a sprocket and chain drive to the engine crankshaft. They work well. There is a bearing on the inside of the chassis side rail, fastened as you can see, by the 2 bolts, either side of the dog.
Please do not PM me asking for support. Please post your questions in the appropriate forums, as the replies it may receive may help all members, not just the individual member. Kindest Regards, Darryl