The brake booster from that ebay link is a not the right part, that part number is 54-74418 and is completely different.
The part number for the 94 is 54-74118, while the part number for the 91-93 is 54-74113.
The 91-93 and the 94 boosters have the same single 9.238 inch diaphragm, use the same Master cylinder, and mount to the firewall the same. The only differences that I'm aware of is that the vacuum input connection moved from the top left to the top right side and the snout that goes through the firewall has a different style rubber boot.
