Just finished lowering the front end on my 74 D100. Need to flip the tie rod from the top to bottom to eliminate bump steer. I have a reamer but wanted to know if there’s a tapered insert I need to use.

Any time I've inverted the taper on tie rod holes, I've only run the taper in about 1/2 way and stopped. You have to leave enough material that the tie rod end seats on the taper with enough gap at the bottom to allow the tie rod end to move as it needs to and the nut can be tightened up to spec. If you go too deep, that is when you get into trouble. The gap left at the top from the original taper that entered from the other direction will be under the nut, so it doesn't seem to make any difference.

If you are ODC and the gap bothers you, you can weld the hole closed, drill a new hole through the weld, then apply the taper from the direction you need it and be done, but that is really way over the top, as long as you don't run the new taper in too deep on the original hole. Gene

Can you simply use a dropped tie rod end? This is what I did on my 65 but I'm not sure what constraints you have on your 74'.

- EM

I never understood the logic behind "lowering" any pickup truck...… mine get that way temporarily when I use them for their intended purpose, then go "back to normal" when unloaded...…

lowering trucks is a fad that has outlived its usefulness.

Says who? If you feel that way, that is fine.
Post a picture of yourself so other people with modern clothes or hairstyles can give their opinions on what you look like.
Are musclecars a fad?

If you are speaking of a tapered insert to put in the unused tapered hole, as a filler, yes, somewhere in my foggy mind I am pretty sure I have seen them, but I do not remember where.
Just that I am pretty sure such a thing exists.

That was a lot of help, wasn't it?

May have been a street rod shop item? Good luck.

Im thinking Speedway Motors would have inserts.

I think van steering arms have the tie rods coming in from the bottom. Been awhile since I've been under one though.