The other day about 1/2 mile from home, My '91 E-250, 300 auto, stopped shifting. I pulled into my driveway, looked under and saw the modulator had fallen out (don't ask how!) I plugged it back in and fashioned a clamp to keep it in place and added fluid. It shifts, but, slips, or, drags going into 3rd. I had forgotten about the little control rod. It wasn't sticking out of the modulator when it was hanging by the hose. Can it shift without the rod? Will it hurt to drive it on the highway with a minumum of shifting?If so, and I am missing mine, does anyone know the demensions, so I can make one.
I would appreciate any help I can get with this. Thanks, Lloyd

 

I just walked out to my toolbox and measured a few C6 modulator pins. They are .125 (1/8") diameter and the ones I have run from 1.58 to 1.66 inches long with smooth round ends. A piece of 1/8 welding rod will work fine. Start with a piece about 1.7" long and shorten it a little at a time till you get the shift points you want. The longer rod will shift later and the shift will get earlier as you shorten the rod. If you have a modulator with an adjustment screw you can fine tune it with the screw. Screwing the adjustment in will make the shift later and out makes the shift earlier.

 

Thank You all

 

Apologies if I'm being improper.
Is that for all C6's?
Munrow

 

Pretty much, also note the color band on it if you decide to replace it. It does make a difference. I don't remember what it is, but there is a diff.

 

I went to Advanceautoparts online to look for a transmission modulator and it shows three different color bands; green, purple and black.
Anybody know the difference?
Thanks,
Munrow

 

You'd have to look at the one in your van to determine the correct one. You may have to actually get them to cross the numbers to see which one you need.

 

Thanks, but I wasn't asking which one I should use.
I was asking if anyone knows what the different colors meant. Could be possible that the differing colors have something to do with how the tranny functions.
Thanks,
Munrow

 

If I remember right, one is for diesel truck, one is for gas truck, and one is for gas car... I could be wrong, but I think it has to do with the length of the rod.

 

The parts store shows all of them available for my vehicle ('86 E250, 5.8, C6). Unless someone posts otherwise, I'm gonna go with rod length.
Thanks,
Munrow