Figure out what the engine, blower, and pump is worth used. The sum of those parts, no more.
From an engineering standpoint - the frame on these units are extremely deficient. You could probably weld some old huffy bike frames together with more rigidity.
You have a direct coupled blower, which to not eat blower output shafts every 400-800 hrs, must remain within tolerances in the thousands of an inch in 3 directions - and upon startup, you can watch the frame deflect 1/4 to a 1/2".
In a nutshell - it's not a hays coupler issue if you keep them greased, it's an alignment (keeping it aligned) issue. Your choices are either having someone add a lot of secondary bracing in this frame and upgrading just about every mount (If memory serves, 4 - 9/16 studs and nuts are all that hold the front side of the engine) - or having someone like Judson take the main components and fab them to a new frame.
- the computer MUST be relocated - along with rerouting / heat insulating of a good bit the wiring.
- if the hx'er diverter is the cable driven model - you might as well scrap the whole hx and get a little giant. It simply can not be made to work reliably. If it is the vacuum hose driven system, you need to install better lines to it and insulate them. Even with that - you'll still be replacing the actuator frequently.
- stock up on temp sensors, I believe they are 180, 240, and either 260-280-or 300 degree ones. You'll go through those frequently as well.
- the upper water box, likes to jiggle itself apart, pad it with some rubber underneath it
- unless your area has very soft water, you have to have a softener - period. There are 3-4 places that will literally scale up within 6-8 hrs of use that will render the heat diversion system useless and cause the machine to hit >300 and shut down. When it gets that high, the second stage heat exchanger actually overheats the nissan - and you are down for 20-30 minutes
- there is so much vibration, any wire, line, or hose, that rests or touches anything, must be wrapped in a secondary hose, or you will be replacing wires, lines, and hoses monthly or sooner.
When it is running properly - it is a fire breathing beast. I ran mine with a rotary tool and wand simultaneously and the unit still had to dump over excess heat. It will suck the shirt off your back. Problem is - you work on it more than it works for you.
Unless you plan on stripping the main components, fabbing up a new TM out of it - steer clear.