I'm trying to understand if all FE flywheels with 184 tooth have a 15.5" O.D ring gear and work in all available manual transmissions that came stock on FE cars and trucks.
When researching my original flywheel used in the T85C 3 speed MT. ND provided the following information on another thread and it was very useful BTW but what about the O.D. for starter compatibility when making modifications?

C5AZ-6375-K .. Flywheel - Use with 11" clutch ~ (6) 5/16" -18 pressure plate attaching holes on a 12 3/8" bolt circle / Obsolete
1965/67 F100/350 352 // 1968/76 F100/350 360 // 1965/67 Galaxie/LTD 352. The ring gear came with the flywheel, but it was also available by itself.
And
C5AZ-6375-L .. 390 Flywheel - Use with 11 1/2" clutch / (6) 5/16" -18 pressure plate attaching holes on a 12 7/8" bolt circle / Obsolete
1965/71 Ford Passenger Cars // 1968/76 F100/350.

I'm working on my 1966 F100 with a 352 and the T85C 3 speed MT.
I want to replace the engine with a 428CJ I happened upon. More about that here- https://www.ford-trucks.com/forums/1...s-a-428cj.html

The 1968/70 428CJ is externally balanced and requires a specific flywheel of C80Z-6375-A (P/N C80E-A) (correct me if I'm mistaken here), what's odd is that this is described on other forums as a 184 tooth 14 15/64" ring gear with (6) 5/16" attaching holes on a 12 7/8" bolt center, and I think the counterbalance weight is 28 oz. Not sure what total weight is.

Does this mean there isn't a flywheel made for the 428CJ and T85C combination and my starter will never engage the ring gear? What are my options here or does this combo actually work? Recommendations welcome.

I'd like to keep the MT as it has overdrive. I also have the C6 that came bolted with the engine as an option but RPM,s with 3.5 gear ratio seems pretty high at 2800 for 65 + MPH. This truck is only used on Friday or Sunday long drives with an occasional heavy foot.

 

I think that all stick shift FE engines and 385 series engines came with the same diameter flywheels BUT the ones for the FE engines had a different number of teeth(fewer, larger teeth than the one from a 385 series engine). A number of years ago I built a 428 for a guy who had it in a '64 Galaxie with a 4 speed. I was worried about finding the right wheel with the 428 weight but I found a brand new one off of E-Bay that fit perfectly.

 

352/360/390 flywheels work on an internal balance 460 (or 429) all day long......the FE flex plates are the same size as the flywheels.

The 429 and 460 use a smaller ring gear on the flexplate though (automatic bellhousing is smaller around at the bottom) so no-go on FE partsfor the autos.

I'm not sure if this is the information you need, but lots of swaps haven't steered me wrong.

 

Does the flywheel for an externally balanced 460 engine use the same amount of weight as the one for a 428?

 

I wasn't aware there was a difference on the external-balance (79-up) 460s other than the funky harmonic damper counterweighted spacer. I know the 410/428 flexplates are weighted but don't think the 460's are/were...just the damper spacer. I really don't know though on that one.

EDIT:

I forgot, they ARE weighted....did a clutch a couple months ago on a 97. Don't know about the actual weight/inch.

 

I called Modern Driveline (MDL) and spoke with a sales rep.

He didn't know what the external O.D. was but he thought if it had 184 teeth, the diameters would be the same. I'm not very confident in that answer.

The A/T flexplate has 184 teeth and measures 15.5". I guess I'll have to see what the flywheel O.D. is on the back of my 352 when I pull it.

 

On my dyno I use a stick shift bell housing for the engine type that I'm going to run along with an automatic transmission flexplate that bolts to the dyno drive plate. That works just fine on an FE so there has to be at least one style where they are both the same. For the 385 series Ford I use an FMX bell housing and an automatic flexplate.

 

Me too. Not dyno, but run stand. FMX 335/385 bellhousing and auto flexplate for whichever is on it. FE doesn't matter as auto and manual flywheel/flexplate are the same diameter.

 

Finally removed the T85N and measured the flywheel. Cleatus12r is correct. The C6 flexplate and the T85N Flywheel are the same outside diameter is ~15.5" with 184 teeth.