Eccentric
Mister Wizard
What does a 909D take?
Large Mount Homelite. 3/8" bar studs. Larger tail profile than the D096/D196 XL-series Homelite mount (even though it's also 3/8 slot). Oregon used to make a 'universal' mount bar that would go on both large frame Homelites and McCullochs. I have a 30" Oregon "Duo-Tronic" bar with that mount. They also made RN bars with that mount. I've seen a few on feebay. Mine came from Mr. Bow Saw.
These are the manufacturers codes for the Homelite mount. Out of production I'm affraid, although there are a bunch of NOS Carlton hardnoses floating around feebay.
Carlton 50
Oregon F014
Windsor HO
GB H
Cannon H.
Here's Acres' listing for the mount:
Bar Mount Pattern: 16