My oem temp gauge failed on my 1986 def 2.5 NAD so I figured I go the VDO route as mentioned here in numerous threads. I read the combined vdo thread, tried search function, Googled, etc and cannot find the correct part number for my truck and seem to only find nas, 200/300tdis info. I've read a lot of "perfect fit" threads with bad info. I've ordered via egauges and jets different vdo senders using the thread size as measured. I've tried 5/8-18 nf-3 and m16x1.5. I'm at a loss and I'm considering simply purchasing a lr temp gauge and new sender to just be done but I'd love to know true or closer to true temp numbers. The oem sender is prc6663. It has finer threads than any of the ones I've received. I'm clearly bolt-screw- thread challenged so I'll admit that to avoid the anticipated beatings for not being an expert. This is keeping me from enjoying my dream truck. I've attached a pic. The oem sender is the one supported by a key. The others are vdos from various.
I've tried vdo 323-026 and 323-417.
Thanks for any leads!