SFBD frame question

I need to know how much to take off the top of the frame rail under the cab using the stock frame to lay rocker not pinch. (89 yota std cab) Ready to cut tomorrow. Already z'd and transmisson crossmember is removed. Thanks in advance guys.

Bump has a pretty good project thread let me see if I can find it

Here check out this thread it should help answer your questions

as long as you have 3 inches of frame, you should be alright. but I don't recommend doing it that way. build you a table, and build it out of 2x3. It's so much cleaner and just a better all around idea.

regardless of what you do, your cutting the floor to actually rocker it. mine isn't cut....guy didnt feel like doing it for whatever reason, so im just going to have a sheetmetal floor built.

Be careful I'm sure you noticed how thin the inside part of the frame is, I could be off but it looks like 16 gauge. I'm scared to have frame rails any shorter then 4".

i'm pretty sure he would run 2x3 inside the stock rail once cut down. I just don't like the look of that. 4 inches is quite tall for an import truck like ours. 2x3x1/8 and 3/16 is just as well under these.

The stock frame is around 4.625" tall, give or take. I've noticed it can vary by about an 1/8" either way from truck to truck.

Thanks for all the info guys!