Hey everyone,

I’ve got the entire donor car, 97 Mountie and the M5R2 from a 98 F150 4.2.

The issue I’m having, is that any clutch kit I’ve been able to get for the M5R2 does not fit the splines on the input shaft.

Having read dozens of forums pertaining to M5R2 5.0 swaps. I understand that a successful combo that has been used is the Flywheel/Clutch kit from a 94-96 F150 5.0. However, this has also failed me on spline diameter.

All combos used were of the Luk brand from Advanced Auto Parts, and I’m currently stuck on this seemingly easy chapter in the swap.

What am I doing wrong? Should I be seeking strictly OEM? Any help is greatly appreciated.

 

I have concluded that the input shaft for the M50DR2 I have has a diameter of 1-1/8”. This is too big for every clutch kit that fits the F150 5.0, at 1-1/16”.

I am able to return the transmission if I somehow ended up with an incorrect M50DR2…? Is there such a thing?

Has anyone heard of this?

 

M5R2(M5OD-R2) should have same input shaft diameter regardless of year
1995 and earlier were 11" overall length
1996 and up were 11 3/8" over all length
Bit same diameter and spline number as far as I know

4.2l Ford F-150 1997 and up only used the M5R2, but are you sure it is an M5R2 by casting number or visual comparison?

 

Thank you for the input! Turns out (using micrometer) the shaft is 27mm wide at the splines at the widest point (peaks).

Where might I find the casting number? I called the yard I’d purchased it from (shelf pickup) and they’d rechecked to ensure it came from the 98 4.2 F150, thus surely making it the R2, as my research has lead me to believe.

Here is the only casting number (with sticker) I can find.

 

27mm = 1.063" = 1 1/16"

 

Mystery solved. A 91 F150 5.0 clutch/flywheel combo works perfectly fine.