Just got this model home, no engine. Can not find this model's manual. It is similar to the 1832 some areas, but that one is a hydro. Mine has very small engine mount hole spacing. Now thinking it may have been a twin also?? Way smaller mount than any big single Briggs and even a K engine. 8hp Briggs is close, but still bigger, so now thinking maybe a twin? Hood is longer space and would fit one I believe. I want to put in a single Briggs, but will have to check the hood clearance maybe on top?
Anyone have a manual to sell, copy, post for others to get or whatever? I'm also trying to find year. It has a Safety switch under the seat and gas tank is in rear, so what years were those requirements needed? Here is serial, which I can't decipher. First time I have ever seen the M at end of it.

1641 129601 M

This frame and steering wheel placement and controls are all much better positions that other Speedex. Seems it would be much easier to ride and stay comfortable while in use. Think I'm gonna like it IF I can get it going.

To let you know, I found manuals for 1640 and other 40's that is same tractor I have, mostly. Seems they had a Briggs Vanguard in it, I think a later model. Thinking might be 93 year,but not sure yet. Not sure how to read above serial for any date and engine gone, so can't date by it.