I have a 26hp craftsman that dies when I engage the pto or let out brake pedal, replaced both and no change, could the clutch be shorting out, I have checked all connections and have not found any bare wires, any ideas

Sears tractor, and many others, have 2-3 safety switches to prevent you from doing something unsafe. There is a switch under the seat that tells the mower if you are seated, another switch tells the mower if you are trying to start the engine while in gear or with the blade engaged. I'd start by checking the swuicth under the seat. The test is different depending on if you have 2 or 3 wires going to the switch, tell us what you have.

I've checked the seat switch and its OK, could it be the ignition switch or can the clutch be shorting out, the clutch clicks loud when I engage the pto when the mowers not running but the key is on,all I can find is seat and clutch safety switch

I left a number out on my model the correct # 917-276071 the seat has 2 wires but checked it and it works

Plese don't use the comment section for your reply, just type in the box labeled ANSWER THIS QUESTION. We have had some changes to our site and that comment box is goofing things up for folks. If you don't have the manual your can get one at http://www.searspartsdirect.com/partsdirect/orderStatus.pd?pop=flush So from what you tell us you can't get the mower to even move since it also stalls when you let out the clutch, right? How did you check out the seat switch, did you use a continuity tester or what?

Yes I tested the seat switch, replaced the clutch safety switch and pto and it changed nothing, I took the clutch safety switch out and if I hold the button down with my finger I can engage the transmission but if I let the button go it dies and engaging the blades makes it die

I agree with Ballenger.
It's the seat switch , you didn't say how you tested it.
This unit could have a open circuit switch or a closed circuit .
Unplug the switch see if it works if so replace it.if not jump it with a wire same thing if it works replace it .LUCK

If it was the seat switch then I shouldn't be able to start the mower at all, correct? Could it be the ignition switch or the clutch shorting out

When you push the brake to start it you bypass the seat switch.
That's why if you set the brake you can get off and pick something up without shutting off engine.

Ill change the seat switch today, would the ignition switch cause this to happen or the clutch shorting out

I agree with DG, still thinking seat switch. Clutch is mechanical, no electric to short. Iginition switch is not going to short just when you move the pto or brake.

Ill find out this afternoon if it's the seat switch, have a new one, I appreciate both of your help