Miata Slave Cylinder Compatability

Swapping out the clutch in my 1990 Miata and discovered that my transmission is not original to the vehicle, it's from an earlier 1990. Now, I note that FM has a slave cylinder for below a certain VIN break (which the transmission is under) and a slave cylinder for above the VIN break (which the car is over).

I ordered the slave cylinder for the later car before I had the transmission out. My question is, how big of a difference is there and should I match the slave cylinder to the vehicle VIN or transmission VIN?

Transmission. The slave only touches the the trans.

Although I think the only difference is the length of the nipple on the end of the piston. Early Miatas sometimes would get a little chirping noise from the piston rubbing slightly against the clutch arm. You can solve it with a little bit of grease on the end of the piston. I don't know if the later slave is likely to avoid this, but reports of the chirping certainly decreased over the years.

Let me know, I know of the difference but never investigated too far :)

Looking at the photos, the only real difference I seem to see is the end of the pushrod on the slave cylinder. Seems like if I swap the pushrod over to the new slave cylinder, I should be fine.