Doesn't really apply to your electric sender and gauge... but...

I am using -4 AN ptfe hose and appropriate fittings to plumb the mechanical oil gauge in my FE Galaxie.

Using a bulkhead fitting to pass thru the firewall.

Ton of options for AN fittings.
Maybe you could run a AN line to a small block/manifold and attach the sender there.

I've had my share of mechanical oil gauges using the supplied plastic line or soft copper line and never had any nasty failures.
But I did inspect those line fairly often.
If the line started to look weak or compromised in some way, I was on it.

My thinking now is the ptfe line should pretty much last forever, as long as I run it right...
ie: clamped down and no chafing anywhere.

More expensive to do it this way but should be maintenance free.

I have also cut a new snap ring groove in a 4 plate drum, to get 5 plates using normal factory type frictions, steels and (thick) pressure plate.

     But it's just that placement isn't really optional so you have to consider the stacking and the placement movement with wear, as it 'is' possible to have a steel catch on the old grove!   

That can happen if you are not "careful" where you cut the snap ring groove.
On a 4 plate drum, you have just enough room to cut the groove for 5 plates, BUT...
You MUST use a factory thick top pressure plate.
That plate "covers" the lower 4 plate groove and there is no danger of having a steel plate get caught in the groove.

The general "rule of thumb" is...

You can cut a 4 plate drum to get 5 factory type plates in with a factory thick top pressure plate.

You can cut a 3 plate drum to get 4 factory type plates in also with a factory thick top pressure plate.

You CANNOT get 5 plates in a 3 plate drum with factory type plates. Or any type plate for that matter...

If you try to cut a 3 plate drum to get 5 plates...

You WILL have a problem with one of the steel plates getting caught in the original 3 plate snap ring groove.


Also beware there are some factory drums that have 2 grooves already cut.
The lower groove for 3 plates and the top groove fits 4 plates.
If you have one of those, you're stuck, you cannot get 5 plates in it.
That lower 3 plate groove limits you to 4 factory plates max.

ALTO makes a "PowerPack" for the direct drum where you can get as many as 7 or 8 friction plates in a 4 plate drum. The ALTO PowerPack uses very thin steels, frictions, and pressure plate to get more in the drum.

     I like this "idea", except where/when slippage exists, because the thin steels can't absorb as much heat as the thicker examples, so they'll likely suffer blueing and warp sooner!  Also, I've had instances where even thicker plates are split/broken so . . . . . .   And the frictions (steel carrier) can't be any thinner as I've had the inner-splines just roll-formed outward and disengaged from the hub.   

Good point about the thin plates, they "can" overheat and warp. However...

I build 4R100 diesel units that have a factory 5 plate drum. (no you cannot swap that drum into a C6, I've tried)

When a customer requests a "HD" 4R100 build cuz they are gonna be towing heavy, and/or boosted the power on the 7.3L IDI... then...

I use the ALTO PowerPack and get 8 plates in the direct drum.

In 7 years of building these HD 4R100's I've never had one fail from having the thin frictions and steels.
The ALTO plates are hardened, both friction core internal splined steel and outer splined steel.

They will pound "notches" into the clutch hubs before the splines fail.

As far as warpage... they just don't.
If the clutch pack slips enough to cause heat warpage of the thin plates,
you have other problems that are causing the slippage in the first place.

That all said... the first time I saw those thin ALTO plates I thought..

"Oh boy, here we go... thin plates are gonna warp" but time has proven them to be very reliable.

And that said... there "are" other thin plates out there for other units, and they "do" have a warping problem.

Not the ALTO ones for the C6 and 4R100.
The increased friction surface area seems to be able to take the heat and provides more/better holding power.


YMMV

     But, it should still have the "4-pinion" planet and the "4/5-plate" clutch drum.   

     Scott.

True that Scott, "most" FE truck units have the 4 pin rear planet.
Some only got the 3 pin. 1/2 tons mostly.

I've never seen one with the 5 plate drum. Not saying they don't exist. Probably only in the FT units.
Not the "regular" FE light trucks.
Most have the 4 plate drum and some were built with the 3 plate.

Heck I once built a 66 T-Bird C6 that had never been touched before, and it had a 2 plate direct drum.
Up to that point I didn't know there was such a thing.
That was in the 80's and I was shocked that such a heavy car would have that.
It was "only" a 390 car... but still... a 2 plate direct drum??? what was Ford thinking.

Never seen another since...

Probably not your issue... but...

My 68 Mustang 390 with a CJ 735 cfm carb would surge at 60-70 mph light throttle cruise.
Tip in throttle and surge was gone.
Ran perfectly in all other aspects.

Had the oval open element air cleaner and a 68 Shelby hood with open scoops.

If I pulled the (converted to) manual choke out "ever so slightly" the surge would clear up.
Choke NOT pulled enough to make it richer. "Just barely" moved the choke blade less than 1/16".

My theory...

The open air cleaner and hood scoop disturbed the air flow into the carb.
Pulling the choke such a tiny amount changed the airflow thru the boosters such that the surge went away.

I meant to fashion a shield in front of the air cleaner to block air from the scoops to see if that helped.
Sadly I sold the car before ever trying this...

where do i find Chris' JR 8V-F?  did interweb search and did not find anything.     Thank You

https://robertpondmotorsports.com/

Top of page is his phone #

Bends in the cable must be large radius and smooth.
No tight bends or kinks.

I've encountered factory cable installations
where using any or some of the factory cable hold down clips,
they put a very mild kink in the cable and cause that kind of bounce.
So mild a kink you would "think" it's ok, but no.

Remove the clip and let the cable find its "natural" position.
Extend the clip somehow to hold the cable in its/that natural position.

This can be tricky if the kink is up under the dash.
Not much room there....

By the same token, a cable that is unsupported and "floating" in space can cause the same issue.
It needs to be restrained, but in natural non kinked way.

C6 used 2 different fittings over the years.
Depends on application. ie; what vehicle.

"Most" C6's had 1/8 NPT pipe to 5/16 inverted flare,
but I have seen T-Birds with 3/8 line inverted flare.
Some trucks too.

The 3/8 fittings used 1/4 straight pipe thread in the case, and either an O-ring OR a tapered seat.

"Some" 5/16 line fittings also used the 1/4 straight pipe thread in the case.

C4's I "think" all had 1/8 straight pipe and a fitting that used an O-ring at the case.

Your C6 "probably" has 1/4 straight pipe that uses an O-ring at the case.

Pics would help.