Oil filter confusion... MB dealer sold me a BMW filter

[86560SEL]

They may all be the same, but I am wondering. Went today to get a filter for my moms 88 Mercedes. I have always purchased my Mercedes filters at the local dealership (its a Mercedes AND BMW dealer). Today there was some guy there that seemed totally clueless. He didnt even know what engine a 300SEL had. He had went around the corner to a computer where I could not see him and he asked me if it was a 3.5L or a 4.3L... I am like, what the heck?! I told him it was a 3.0L inline 6. He punched more on the computer, got up walked toward the back, mumbling, "I dont think its a 3.0". Another guy behind the counter told him it was a spin on filter and to give me (and he said some part #). The man came back out and asked me if I minded using a BMW filter and I said no, as long as it works, but I am wondering will this filter be OK for our Mercedes? The filter he gave me looks longer than the Mercedes filter thats on there. It says made in Austria (and I think the Mercedes filter was too, (may have been Spain), but they may be the same manufacturer. I dont know. I wanted to be sure though that this filter would be OK for the M103 engine. Oh, get this... when I last bought a MB filter, it was $7.00... this time he came and said, the BMW filter is cheaper anyway... then charged me $16.01!