Fuel Pump Difference?

[79TurboCutlass]

I have 2 Walbro fuel pumps. One I purchased from Full Throttle about 4 years ago, F2000169 stamped on the body. The other I purchased from Racetronix last week, GSS340 stamped on the body. The FT pump has a smaller, offset pick-up, while the Racetronix has a larger centered pick-up. Why the difference?

 

[87GN_70GS]

A production change was made to the 340 and the new model number assigned to it is 0169. The 340 was originally a mustang pump and the inlet had to be machined to accept the GM style screen. Walbro made the inlet smaller (to avoid the extra machining step) and placed it offcenter so it better fits the GM hangers.