Begin by removing the small control wire that activates the glow plug controller. Then replace the fuse. Now use test light to confirm power gets to that connector and see if the fuse blows again.
With the wire disconnected from controller, if fuse blows, then you have a short in the wire somewhere. I really like the power probe 3 master kit for electrical diagnostics, and locating opens & shorts.
If the fuse doesn’t blow, then you may have bad glow plugs or wiring from the controller to the plugs. Key off, If you reconnect the wire you just tested and disconnect the 8 glow plug wires from glowplugs ensuring that all 8 are kept well away from grounding out (wires and ends) then attempt turning to glow position again. If the fuse doesn’t blow then the glow plugs or plug “wires” (actually fuseable link wires) are shorting out. Normally the wires look ok but you can feel where they are messed up inside the rubber insulation. If the wires check out ok, go agead and replace glow plugs remembering to put antiseize on threads of new ones.
If the fuse does blow again, then suspect a short in the large supply wire from battery feed or the controller itself. In this case normally the controller.
A common mod is to chuck the controller and just use a heavy duty starter solenoid that is rated full duty. CAUTION. This requires a toggle swith inline to the solenoid a tion wire AND requires self limiting glow plugs. Without the toggle you control manually every start the new solenoid will fry in no time. Without the self limiting plugs (the best choice regardless) the plug tips can break off inside the cylinder and ruin the engine.
It’s been 4 years since I worked on one of these. Good close up pics of the controller and I could id which wire does what (if memory doesn’t fail) to help if needed.