I used hydraulic hose. Its rated for what, 2500 PSI? And it's pretty tough on the exterior so it's not as likely to be chafed or cut as regular trans cooler hose or fuel line. There is also a 500 psi hydraulic hose that is a little cheaper but doesn't have the strength, but still is a million times better than parts-store cooler hose. Mine's been on the car way too long (over 10 years now), and I'm currently upgrading to braided as we speak. Just standard braided is fine, I'm told. Only reason I'm upgrading is I just don't feel confident with 10 year old lines going a buck forty and change at the traps.
The hose that I use is "low pressure Hydraulic hose" - trade name is "Push-lock hose" it is easy to seal with a hose clamp and good to 250 psi minimum. You could use the "medium pressure Hyd hose" good to 2750 psi or so but you have to have larger bends in it and it is difficult to get it to seal with a normal hose clamp.
Push-lock hose is also a lot cheaper - you can afford to keep 25 feet of it on hand.
<font size=-1>[ This Message was edited by: PaulS1950 on 12/1/06 10:24pm ]</font>