1999 M750 Lower Triple/Fork clamp compatability

Hi this Geno from Henderson, Nevada
Bike is a 1999 Monster 750, carbed model
front end is the 40mm USD Marzocchi non-adjustable unit

came home from a ride on the monster and discovered the lower triple tree/fork clamp cracked all the way through!
Haven't laid the bike down but showed evidence that the PO had (Ducati dents in tank, broken foot pegs...)
So this front end is the one that I bought here from a fellow board member (Thanks SP3!!-The front end is just great now the triple is roached!!!)

I have a lead from a close by salvage parts place on a complete upper/lower triple tree.
The donor bike was a 2001 M750.
The lower triple Fork clamp on this part is 54mm where the stanchion lives.
The lower triple bottom is marked part # 3423.004.1A.

My 1999 cracked lower triple is also 54mm
The part # on my lower triple is not the same it is marked 3423014.1A.

I believe some of the M750 models had adjustable showas, not certain.
Does anyone here know can I buy this part and retain my top triple as is or even swap the whole thing out after cleaning/repacking the new parts bearings??

Thank you in advance for the advice...I am checking the manuals and parts fiche I can find but most donot go back to the 1999 models for part numbers.

I will try to attach photos in the hopes that maybe one of the good board members here can diagnose what actually happened to cause the lower triple I have to crack.
Of note: i did use a torque wrench when installing the SP3 donor bike fork tubes/stanchions. However I used stainless steel probolt fasteners and did put some anti-seize on the threads. Could over torquing as a result of the threads not being dry be the resulting crack??

Many Thanks!! Ride Safe & Enjoy!!! -Geno