1850 Diesel Tachometer

[Mark Benware]

The 1850 Tach died, upon further investigation it was determined to be the key between the aux drive shaft and the tachometer adapter was incorrect (someone had used an old broken drill bit, new part #158762A) I have procured parts and have a question about changing the "pin and peg" (159221A and 159222A) First off is it possible to change this without removing the aux drive shaft, my parts book and service manual does not make it clear as to the procedure for this. How bad is it to remove the aux drive shaft?
Thanks for any help

 

[BM]

The female drive coupling in the front of shaft is pressed in stuipdly tight. if you have the drive shaft in the vise and a good pipewrench and heat you can get them out, but they're not pretty when you're done. a dowel pin puller won't even come close to getting them out.