Delco starter overhaul.

A little end play is fine, the motor will be pulled into the center of the pole shoes by magnetic force, that will be countered by the drive being thrown into the ring gear, by the inertia drive. (at least on the bigger K's
Checking at 180 deg doesn't tell you much on a four pole motor. There are 4 windings in play at any one point in rotation. The windings are 90 degrees apart but it is almost a dead short across the winding. An Ohm reading would show and open, but not a cross short to other windings. That is where a growler comes into it.
180 degrees apart would be more applicable to two pole generator or a small two pole motor. But even there, it really doesn't show much.
When sitting still, a series wound starter motor is as close to a dead short as you can have, and not be a dead short. As soon as it starts to rotate, the effective resistance rises, if left to spin free (not a good idea for long, the speed will try and pull the armature apart) it will eventually reach a speed where the effective resistance is high enough it will draw under a hundred amps.
A series motor will self destruct if kept at a low speed for a long time. For this reason for longest life, the sooner you can get it up to speed under load the better. Cables and connections between the battery and motor are the primary source of current drop under load.
I had 3 ought cable left over for my semi's and ran that from the battery directly to the starter ground (one mount bolt, 3/8" bolt, and the solenoid switch. The larger K's use a solenoid (so called "Ford" type) in place of the starter mounted switch the flathead used. I had a four ought (0000) cable that was the right length that worked from the solenoid to the motor. If I was going to re-cable the truck. I would spend the money for four ought The down side is it as about as flexible as EMT conduit. 0000 welding cable would be more flexible but risks the little wires in the cable breaking over time, a trade off between flexibility and durability.
One of the cables I pulled off was original and it seamed to be double ought. It is likely good enough, but remember IHC was the one that ran the ground to the frame and a strap to the engine! They were still doing that in 1989 on my 9670 semi, and it still caused problems!
Heavier then minimum cabling gives you a little room for things not being perfect. The fact that my 269 cranks well down to at least the teens F with 15w-40 in the crankcase, is reason enough for me to spend the extra on heavy cable.
If you already have the two ought, and it is in good condition I wouldn't change it unless you have a problem. Not many are going to drive these truck in zero deg weather, although I have driven mine for 500 miles in that weather! I wouldn't recommend it from a comfort standpoint and the defroster has trouble keeping the windshield clear!
As for politics, no we are unlikely to agree, but that is not the primary thing that brought us to these boards, and I too am glad that will not come between us when it comes to old IHC's.

One thing I should have add to the above tome. To check the system on the truck. Pull the coil wire, and crank for 15-30 sec, then run around the truck and feel all the connections and cables. Any that are hot are a problem. It will show a bad connection or a bad cable easily. If the cable is warm all the way along, it is undersized.

Thanks Again. Just curious what IH trucks you have.

Too many if you ask other people!
I have 2 K-7's one is a late '41 or '42 and the other is a '48.
I have a '73 Fleetstar which will likely get scrapped
I sold two 9670's a year ago '83 and '89 when I retired
I have a '92 Marmon which I hope to sell
I have a partial 50's Dart oilfield truck I need to find a home for. Good cab but missing rears and frame has taken a beating over the years, as any oil field equipment will.
Of all, the K's are the ones I'll likely keep around. One is a gin pole truck that is all too handy, the other is a flatbed that comes in use also.
Attached is a pic of the '48 pulling the trans on one of the 9670's with the other in the background.

Thanks. I forgot you had a lot of bigger trucks. I think I remember that from some of the threads. I have too many also if that is possible.
1926 S26
1926 Special Delivery Pickup (Titled as 1 1923 for some reason)
1929 Six Speed Special
1938 D35
1941 K1 SB
1941 K3 LB
1946 K2 LB
1949 KBS5
1956 S120 4x4

It is 5 deg F now after being near 0 last night. We are supposed to get a storm Wednesday night so I wanted to make sure the '42 would start. No ether or starting aids, 6 volt battery only, and cranked and ran without help. Just goes to show that they didn't sit around waiting for 12 volts to be "invented" they could do the job with 6 volts.
With they gas we have today, it evaporates out of the carb very quickly when the engine sits. It took a little cranking to bring the fresh gas to the carb before it would fire. Still had no problem.
I had the clutch depressed, and it did stall when I let it out too quick with the trans in neutral, It takes a bit of power to move SAE 50 oil in the trans when this cold.
Thursday and Friday our highs are going to below 0 and I want to be sure I can move the truck if I need to plow.

Does your D 35 have the FAC in it? 241 or 259? I know the smaller D30's had the flathead, but I don't know where the cut-off was for the OHV.
I am always surprised at how forward thinking IHC was in the early days. The FAB had insert bearings, wet liners and OHV when most were still flathead and some with Babbit bearings.

I believe it is a FAB241? Was that not the engine before the FAC241?

The engine number with the series should be stamped on the block just under and between #1 and #2 sparkplug.
I thought, but could be wrong, the FAB had the gear drive generator and the distributor driven off the back of the genny.
I think the 1st build was 221 CID or may be 207? When it got bigger the distributor moved to over the valve cover. The engine was not designed for the distributor to be driven off the oil pump drive. The oil pump was driven off the inside of the cam shaft. Other engines IHC designed, had the oil pump drive on the outside of the cam which allowed room for the distributor. Their only option when they gave up on the gear driven genny/dist or Mag, was to extend the shaft above the valve cover to allow enough room for the distributor. I have seen a listing for a mag for a FAB in a catalog, but never seen an engine with one fitted. I imagine they would have been more likely on a power unit than a vehicle.
The later engines could be 241 or 259 in the FAC series. the earlier FAB dates back to the early 30's. The FAC lasted until 1941 and then the dryliner BLD took over and that can be had in 250 and 269 CID.
I don't know the cut-off dates for when the FAB and FAC were retired, except that my K manual shows the 1st K series had the FAC in place of the BLD. Easy to tell apart at a glance, as the FAC has no core plugs (Frost plugs) and the BLD does, The FAx series, the core sand can be shaken out from the inside before the wet liners are installed, the BLD has the cylinder already formed (for dry liners) so core plugs are required to get the casting sand out.
You have an interesting collection. of old iron.

I will take a look. Could very easily be a FAC241. I have a few S series chassis with running 240 and 264. My 1956 S120 4x4 has a 240 but it is stuck and been soaking for a year. I need to take the head off and look and if things are bad I will swap it out. All of the valves are free on it and the cylinders look clean so I am surprised it will not free up.

I also just saw your post on the 6v being good in the day and still good today. Many times it is just a misunderstanding on what is needed to get it to work the most efficiently.