Confused by drivetrain compatability...which derailleur do I want?!

Ok, here's what I am running...

CRANKS: Shimano Hollowtech XT w/ Octalink BB (rings stamped "Mega 9")
REAR DER: M950 XTR
REAR COG: 8-speed

So...I need a front derailleur. I know I need 1 1/4" and top-pull. Aside from that, I am confused by (1) the model numbers, such as M750, M760, etc, and (2) not sure if it matters if I get an 8-spd or 9-spd unit.

I was looking for an XT, unless I can find XTR really cheap. Can anyone help me out? Thanks in advance!

 

What bike are you building and what is the seat tube diameter?

 

The bike in my sig ('05 KHS).

I know the sizes are correct, it's more the options of models I am concerned about because I don't know how having a mixed drivetrain will affect shifting performance, or if certain parts will work together or not. Post size is 27.2mm.

 

Whoops, didn't see that you had listed the diameter.
The 8 vs 9 shouldn't matter much for the front.
I may have something. I have a 2001 all-steel ST frame hanging in the garage. 9 speed.
I'll have to check tomorrow night after work.

 

Cool, let me know Shecky! Thx!

 

I have both LX and XT-750 top pull derailleurs, but they are 1 1/8".
Skinny steel-tubed softail. Sorry to get your hopes up.

I loved riding it. I'm sure you will too.

 

Yeah...I actually still look for old steel bikes for fun. I would love to find a Bontrager Race Lite or a Ritchey P-21. Those were hot bikes back when I was racing.

Anyway, thanks for checking, I appreciate it! I'll call the Path today and see if they have something lying around.

 

Hey Sean. Did you get that bike built yet? You invited me on this hellish ride, so you better be there!

 

I am running an 8-speed setup like yours with a 9-speed front deraileur. It works fine, but it was a total BITCH to get it positioned right. It had to be absolutely perfect and the 9-speed setup directions aren't optimized for the 8-speed spacing and such. If you can find an old 8-speed grab it. Otherwise, I think the 9-speed would work. I had to pay a mechanic $10 to dial it in. It was some young kid at Jax, too, which really pissed me off...