I changed the neutral safety switch (70 b body)last night and had to file the center pin down on the after market switch to get the reverse lights to work. Drove the car to work and everything was fine until i tried to park in the lot. went to put car in drive from reverse and it will not go in drive,is the NSS binding up? on the linkage in the trans?

Some of the switches are year-specific, and need the correct actuator in the trans to operate.

You probably have a 68 or earlier trans/valvebody which doesn't have the plastic "comb" so it can't use the later style NSS..

car is from what i see a untouched 70 b body with 904 trans. it is binding up inside ever so slightly. when you put pressure on the shifter and loosen the NSS a little it clicks into drive. When i have the switch loose everything works, funny thing is it all work last night while getting gas and driving in to work this morning, When i put the old NSS up to the new NSS they are identical except for the center pin being longer on the new NSS.I filed it down so the reverse lights would work last night and now this. FUN FUN FUN

i not 100% on this one but when i replaced me NSS there was a plastic tapered washer of some sort on the old on and i put it on the new one could that give you the extra space.

Also i had a 68 and earlier trans in my challenger with the later switch no problems getting into gear but the back up lights were own in every foward gear.

Lastly i think they make 2 different 3 prong switchs on was a little longer then the other. or just return you new NSS and get a different brand good just be a defect.

so i drive the car home at lunch time and when i get home the car shifts great 20 times back and fourth, i tighten the NSS switch up and now no reverse lights again FUN FUN FUN I left it and went back to work.

I've heard that some of the current aftermarket 3-prong switches are too long and need spacers to work correctly.

Filing a center pin that is too long leaves a square end with sharp edges, the sharp edges can dig into the gap between the metal contacts in the plastic shoe and bind the shifter.

As stated, if you do file that center pin... you'll need to radius the pin end...So if you did'nt mabe the end is hanging up in the plastic plunger and not droping when it's supposed to for the rev lights.. Check to make sure that pin slides in and out freely reguardless of the plastic plunger position..

Yes i drove it tonight and everything worked fine, i had reverse lights and it went in gear every time. wierd 40 year old cars. yes i filed both the pin & the plastic plunger but tried to keep the same contour shape. We will see what happens in the next few days.