364 Hydraulic Unit Pre-Repair Questions

Have a 364 that the draft spool is broken where the linkage attaches. This results in draft spool applying "full up" to the cylinder constantly.
After draining the hydraulic unit to have a look around we found the draft spool broken at the linkage attachment point and the small chain that attaches the control valve to the rockershaft arm broken at the rockershaft end. Not sure where chain attaches at control valve end.

Now my questions...
1. Does the chain attach to the draft linkage or the lift spool linkage and whats its purpose? IH parts labels it as chain-safety. Chain looks to have been broken for sometime possibly. Have the Blue Ribbon manual and its not to clear in this area.

2. Are we better off trying to find a entire hydraulic unit from a salvage yard or repairing this one? Draft spool and oring kit from IH going to run over $320 not counting the chain which may not be available. I know a salvaged hydraulic unit is akin to buying a "pig in a poke" Have no idea what a entire hydraulic unit from a yard would run or even if we could locate one.

Sorry for such a long post. Really looking forward to the opinions/experience on this forum on whether to swap out with a salvaged hydraulic unit or repair what we have. Any and all opinions are welcomed and greatly appreciated since this is my first time into the hydraulic unit control repair.
thanks in advance
BMD

Hi BMD, are you planning on plowing or cultivating with this tractor? The reason I ask is a few years ago there was a B414(basically same hydraulics) owner that had hydraulic control problems and since he wasn't going to be plowing or cultivating he fabricated an external hydraulic cylinder to connect to the rockshaft arm much like a 350U, turned the hydraulic valve in the front of the seat to use the remote outlet. Connected cylinder to remote outlet and was good to go.

My thoughts
JimB

CaseIH.com search for parts will be one way to get a view of it. A repair manual is most likely what is needed. Some libraries have them and a photo copy machine while you wait for yours. If I knew the answer I would be more specific. JimN

I have the IH Blue Ribbon manual and the IT manual for the 364 currently. The problem with the IH online parts catalog is the detail leaves a little to be desired. When we get the unit removed and the lower inspection plate off it should become clear where the chain attaches to on the linkage.

Guess my primary concern is whether to go with the repair on the hydraulic unit or try to find another complete used hydraulic unit and swap it out?
Would hate to try repair and then find out later that the best way was to swap it out from a salvage yard or swap it out and later find most people just repair the control valve. Trying to decide on repair or replace as my first plan.

If parts I need are not available or I can not find a used hydraulic unit guess that will eliminate one of the options.

thank you for your advise.....
BMD

Mainly used for plowing and some bush hogging so I guess I'm going to have to replace or repair the existing hydraulic unit.
But that is a truly novel fix for a failed hydraulic unit.

thank you
BMD