Mower deck is exactly like picture in first reply by moderator, (but with more rust) am missing parts shown in snow on right corner. Can see that those parts pivot idler to engage belt drive, but not how the slide rod actually holds idler in position, or if any spring in the system to account for movement as deck follows ground.
The mower deck manual on Speedex site shows mower like mine in picture, but the diagrams do not match with the drive arrangement of the unit their picture. Diagram is dated 1971, and may be for a later version.
Am attaching a couple of photos. Tractor did cleanup pretty good. It is not stock. I stretched it about 4" when first reassembling it 10 years ago as it tended to rear back on me when plowing up hill. Engine is 8 hp B&S that I had on hand, and main tires are now 7.00 x 16 and filled with RimGguard with new old style three rib tires on front. In current configuration it is more of an S23 than an S14. Have Speedex cultivator and plow blade, and a third party cut-down moldboard plow.that fits. Initially bought the tractor as a rusty old pile of parts when moved here thinking to use it to raise some veggies. Rabbits got most of those, so gave that up, and tractor has been mostly in storage since.
Picked up a very cheap Case 220 last year when needed something better to haul a lot of dirt from ditch cleaning operation. Was about to take old Speedex to metal recycle place last fall but engine started right up and found source for new tires, so did major clean up on it. All complete but for the mower deck. I can design something that will work for this, but would like to make near original if possible.
Also have a much modified Simplicity Wonder-boy (1959 or 60) that is still primary lawn mower here. Distinctive cover over rear mounted engine was missing when i got it about 1975. Now on third engine. That mower may get a clean-up next winter.
Meanwhile, any info on how that sliding link that moves idler wheel to engage mower drive works, would be appreciated.