Mercedes Benz 1989 300E Catalytic Converter Help.

[vexman2k3]

I just bought this car and it happened to fail Ontario's Emission test. It's a Mercedes Benz 300E 4dr 1989.

The people at the garage said I need to replace my catalytic converter and I also need to buy a new O2 sensor. They can't go on with the diagnosis as to why my car failed the E-test without those parts. The problem is, they want to charge me $1100 CDN for the parts, and $250 CDN for the labour.

I have seen catalytic converters for 50% - 80% cheaper than the mechanic's price. So my question is, do I need a Mercedes Benz 300E specific cat/con, or could I just buy one of those universal ones and get my mechanic at work to hook it up for me? I don't mind getting a Bosch O2 sensor.

Please help me. I appreciate any help offered.

Thanks a lot.