Yes, that is the correct part. I ordered some and installed them on a PCR and a 75B.
The new rubber bases work great on the PCR because the metal base on the 14 round mag hit the middle of my little finger. The rubber fits my hand much better because the rubber base provides a little longer grip.
On an alternative note, the new bases seem useless for the 16 round magazine in the 75B. My hand never hit the metal mag base anyway and all I did was make the gun bigger.
Rest assured. The new bases fit fine in both pistols and only required pushing in the pins to release the original metal bases. They work fine for their intended purpose. I only paid $4.00 each (plus shipping) because I bought four of them. I will also report that the "rubber" bases are a hard rubber, not even as soft as the rubber grips.
Sancho