Uh,,,Morg,.,,,,you have a Summers gear drive I think. That picture is a Milodon all right...but it for a ford 351C. BBC Milodons have idler in cover.
Used them all...they all work. Gofastracer is a fan of the Pete Jackson. He will be here with a commercial shortly. LOL.
Summers and Jackson fit under original cover.
Milodon, Erson, Donovan all require their cover as idler locates in it.
There's a copy of the Milodon called a Muldoon (or something like that). Wouldn't be afraid to use that one either. Nor would I be afraid to use the IWIS chain setup out of Austrailia.
But no damn cloyes.
Knew it was different, thought it was a different model. My bad.