New MP bars, OEM lower arms, undamaged chassis.
Bump stop out, arm at full droop, all per FSM.
Even disconnected sway bar, shock, loosened strut rod & arm pivot nuts.
Bar goes maybe 1/3 into the hex on the arm, then pretty much stops.
Cleaned hexes, messed with floor jacks to line up hexes (prevent nose droop), clocking looks OK...
The hex on the arm end of the bar actually tapers larger.
The rear hex is consistent, and the bar passes through the rear hex without much effort.
Turning the bar around end-for-end, still only goes into the LCA 1/3.
Fascinating, or another word that starts with F...

If you have everything apart/loosened that much already, maybe just remove the LCA all together and see if the bar slides in then.

I had to sand off the powder coating on my hex's to get the bars to go in. Be sure to grease the ends to slow down corrosion.

i usually use a wooden dowel or something to tap the bar from the rear to get it seated into the socket in the LCA...

Not an unusual problem, especially with used parts. Sometimes torsion bars are bowed which makes them more difficult to align. I assume you checked the obvious and have the L and R side torsion bars on the correct side of the car. If you have the lower pivot nuts loose then just go ahead and tap on the LCA pivot stud to unseat the taper so you can wiggle the arm around a little bit. Once you get them wiggled into position just tap the torsion bar home if you can't do it by hand.

Andy - New MP bars, LCAs & susp previously restored, just changing out some .840 drag bars for .920s.
I think I may have figured it out:
Went to LF, pulled the TB, slid new one in, ended up having to rotate the adj lever down, bingo.
Adj lever was pretty tight even with everything backed off - C-clamp came in handy.
Gonna get back on it after lunch (yikes, it's 3PM) and try that on the RF.

And yeah, on the RF TB, had to sand through some powdercoating and a couple of high spots.

I would suck as a flat-rate wrench !

Yup, that was it: rotating the adjustment lever down a hair made the difference.
Last 1/2 inch was easily handled with a dead-blow and a rubber-tipped punch I made.

What sucks here is the powdercoating. That’s a thickness problem that was never in the equation.

Grease both hex ends or it will make noise.

I have a torsion bar socket tool made from a crankshaft bolt that allows me to adjust the position of the socket. With the tool it is easy to rotate the socket into the correct spot. But even then, if the bars are bowed a little bit or have some thick paint or powder coat on them it can be a tap fit.

I did, including the backside of the rear hex per FSM.

How will a constantly tensioned bar be able to make noise?
The grease is to seal the metal from water and outside elements, aided by a rubber seal and a simple nylon cover at the rear anchor.

Tensioned or not there will be flex that can cause noise.

When you drive the torsion bar and control arm is constantly moving. Also when you go from forward to reverse the control arm moves. Also I installed bars with no grease, but only once. It was very loud.

Ask yourself why would Chrysler put that thick heavy grease in both ends of both bars on every car they made? That’s a lot of time. It was a very necessary step.