After messing around with various wrenches, I went and got a inner tie rod removal tool from Harbor Freight. No matter what I do, I cannot loosen the inner tie rod. I've tried a longish breaker bar and the air impact gun (probably a bad idea, but I was desperate). Am I missing something like I need to apply a counter torque, it's a left handed screw, or there is a pin somewhere? I have read posts who say yes use counter torque and no. I have instructions obtained from a different web site, but this job is pretty straight forward, I just can't get the damn thing off! Help!?

A thing of note is my engine bay tag right side 5th row ends with a "5" which I think means a SMI rack. When I cut the boot off, I saw TRW stamped on my current inner tie rod. The replacement looks identical, but I haven't seen the threads on the old part.

 

Inner tie rods on any car can be really tight! Often the inner tie rod is staked (that is, the edge is upset with a punch) and that makes it really hard to get them loose.
I've found the best tool for the job is a Stillson's wrench, it grabs tighter the more load is put on it and you can jam it against the body somewhere whilst you crack that jam nut off.

 

when i did mine, i had to cook the jam-nut off with a torch. maybe you need to carefully heat it up.

 

THANK YOU, pipe wrench did the trick! Another multi-functional tool added to my collection. Cheaper than the inner tie rod removal tool and more effective. I've never used one before so at first I didn't realize it's meant to go over round parts. For anyone who comes across this thread in the future because you need to replace the inner tie rod, use a pipe wrench. You have plenty of room down there and it's easy to use (self ratcheting!). Put it over the large round part of the tie rod next to the flat.

Here's a summary of sizes on my 99 C70 with SMI for reference:
outer tie rod ball joint nut - 19mm
counter torque for the outer tie rod ball joint nut when tightening (from FCP Groton) - 7mm (this will probably be different depending on replacement part manufacturer)
jam nut securing inner and outer - 21mm
inner tie rod to rack - 1 1/4" (but use pipe wrench on the round part instead. I got a 14" pipe wrench and it's good leverage and doesn't take a lot of room to swing)

 

I just wanted to say thank you for this post, I was at a dead end. The pipe wrench did the job for the inner tie rod. You are awesome!!