Serpentine belt replacement?

I have a 97 f150 with a v6/4.2L (w/ AC). It has 8 pullies. I need to replace the belt and I think the people at my local auto parts store gave me the wrong one. Which do I need and where can I find a diagram?

It is K061031 and the one they gave me says 1030K6

I figure I will have to go up there. I have the belt on in the same fashion as the last, but there is so much slack it can't be the right one. While I have your attention. When the belt was on?

Hi Can I bypass the air conditioner pully by using a smaller belt pully froze up no money and I dont need the air

THANKS BMRFIXIT

A friends 1995 f150,302, 5 speed w/air, has a problem with the serpentine belt slipping off the crankshaft pulley. He has replaced the tensioner, crankshft pulley, harmonic balancer, has recently replaced the alternator. The belt looks like it will come off, slidding to the front of the crank shaft pulley by about a 1/4 past the the pulley on the bottom.
To me the tensioner looks to be at a slite anlge pointed out, but even the the new one looks the same.
Any ideas would be appreciated. He's driving me nuts with this.

I have replaced the auto tensioner, pulley, belt and checked all the accessory pulleys with no visible signs of a problem. Yet the belt still comes off every now and again. What can be causing this?

I need to find the diagram for the serpentine belt on a 1990 Ford F-150 V8 5.0 & A/C. Diagram is not under hood or near radiator. Does anyone know where I can find one?
Thanks

Thanks for the help and for the quick response!

I need to put on my serpentine belt and I dont know how to get it on. I dont have a book and it doesnt show a diagram on the hood. So I need 2 know how to put it on?