Well, Terry, the topic was on engine-driveline couplers... and I did my 109 a year and a half ago... that was what I came up with.
The 109 had a common problem- the engine coupler (pin in slot arrangement) had worn the pin seriously thin, and the slot had about 40 degrees of rotational slop too. The end of the driveshaft was also 'bell shaped' from wearing against a crooked load. In my 109, Nothing was bent, nothing was loose... but looking at the driveline, the line didn't run straight from the git-go, so it was only a matter-of-time before the OEM coupling method would die.
One of the not-so-obvious problems with the original coupling method, was that... in order to remove the driveshaft, the engine would have to be pulled out, at least partially... that'd allow the 'anti-launch' pin to be disengaged from the 'rag' joint at the hydrostat end. I didn't like this.
The STOCK driveline doesn't run perfectly straight, AND, when the frame flexes (and it does), it becomes much less than perfectly straight, and the front coupler leaves NO compliance.
The last problem, is that they put a 4" rag joint about 3" from a 4.5" cooling fan. I didn't think much of that, either.
So, I dealt with all the issues at once. IN selecting parts, I found that the most suitable combination of parts, was to use a rag joint (which allows for a little fore-aft compliance) with a U-joint (which allows non-coplanar drive with minimal wear). I resolved the coupler-pin issue by moving the rag-joint up to the engine-end, and mounted this joint in back, with fan right by it, now unrestricted of airflow to the hydrostat. As a bonus, locating the grease-fitting to the Hydro side allows me to remove the front joint's allen-bolt pin, then I can unbolt the rag-joint, slide the driveshaft almost 3" straight back, drop it to one side, and slide it forward, and out of the tractor, without ever touching the engine mount bolts! It's a stout, smooth, and very quiet driveline, has greater tolerance for malignment, doesn't adversely put any 'funny' forces on the tractor, and costs same or less than a new rag-joint assembly. It doesn't have the risks of being 'launched' like a broken LoveJoy (they specify that the driveline MUST be supported at both ends) and doesn't make the racket or have the speed limitations of a double-link sprocket-chain-type coupler... plus, it's easier to install and remove than the others.
To it's downside, it does put the fan a tad close to the lift arm, which can be resolved easily by trimming the lift-arm's pins and skimming a little off the fan. It also requires a little TLC in getting the yoke drilled square with the existing drilled-tapped set-screw hole, and you'll need to make the 'special' allen-head pins that retain the U-joint on shafts, but it's not too hard to do, even with just a drill press and 4" angle-grinder. Moving the rag-joint to the engine-end requires some cutting and welding, but nothing that can't be done with ordinary tools and a savvy operator. When it's all done, it looks stock!
