I have had success rebuilding both the large and small style original pumps, but in the end, it is still a part that has seen service for many years and there are really no guarantees it is going to last as long as it first did. The only real long lasting repair with good assurance it will not leave you stranded is to replace the fuel pump with a brand new Bosch brand designed for the car. These are readily available and the prices are about as variable as the number of sources. Yes, they are expensive, but at least they are available. A rebuilt pump makes sense when you feel more comfortable having a spare in the trunk for that time when your first team pump decides for what ever reason it wants to take a "breather". Now if originality is an issue and you have the long pump, you're pretty much stuck with having to go with a rebuilt one. For all intents and purposes the short and long style are pretty much interchangeable, although I have heard that the big body Benzes with the larger engines tend to run better on the long style pumps