I'm posting this information in the hope that it will shave a little time off the process of installing longtubes and an ORY pipe on an OBDI LT1 Fbody.

My particular components are as listed below:
*Hooker Super Competition longtube headers (part# 66-2231) w/ O2 bungs from Thunder Racing
*Stainless Works aluminized steel Off-road Y pipe (Summit part# STW-CA937HKA)
*I only used the included collector gasket from Hooker, instead of the header gaskets I used copper gaskets from Summit (part# SUM-111407).
*EGR block off plate from GM
*(2) Bosch Oxygen Sensors (part#15703) to replace originals.
*(2) Caspers Electronics 24" flat 4-pin oxygen sensor extension cables (part# 109011)
*Taylor fire resistant sparkplug boot sleeves (part# 2522)
*(2)3" inner diameter/3" outer diameter exhaust couplers from Autozone
*(3) NAPA 3" heavy duty exhaust clamps
*Gobs of high-temp anti-seize compound
*High temp RTV sealant

Notes on components:

*I would not recommend using this model ORY pipe. I don't know if any others perform better, but cutting at multiple points was necessary to get it to fit. A properly fitting Y pipe may have eliminated the need for at least one of the clamps and couplers.

*Oxygen sensors may be reused, but I had no luck removing the original from the passenger side manifold and the driver side O2 sensor was pretty fouled.

*24" O2 extension cables might not be necessary, but 12" looked like it would be cutting it too close.

Some Socket Sizes:

8mm Starter solenoid.
11mm Steering linkage bolts.
13mm Starter solenoid, serpentine belt tensioner, alternator battery cable.
15mm Cat hanger, alternator.
3/8 Dipstick mount.
7/16 Header bolts.
1/2 EGR.
9/16 Collector flange, manifold, starter bolts.
5/8 (deep) Spark plugs, exhaust hanger, Engine Mount Straight-through bolts.
11/16 Engine Mount Straight-through bolts.
7/8 (Crescent or open ended wrench) O2 Sensors.

Tips for installation/removal:

*Don't bother putting the starter back in until just about last. You'll appreciate the added accessibility to the sparkplugs, wires, and header bolts.

*Long before installing the headers I added an LT4 knock sensor module, it may be necessary for decent performance after the installation if you don't have one already. Available from GM service centers.

*Raise the lowest point of the K member to at least 23" and you should be okay.

*The headers should fit through okay if you remove the engine mount on the side you're installing on and raise that side of the engine about 2 inches, one side at a time.

*Before bolting down the driver-side header, disconnect the steering linkage and fit in the pipe for cylinder 1 if necessary for your application.

Any other questions, let me know and I'll do my best to help!

 

Thanks a lot, I've been searching for something like that for a while. I'll be doing this in about a month.

 

Glad I could help LSUxBlake. If any questions arise as you get closer to installation date, let me know. I'm not an expert, but like I said, I'll try to answer any questions I can.

 

A little something to add. A 15mm deep socket is important to remove the cats and dont de afarid to break those bolts off! broke all mine, actually easier then screwing them off all the way on the rusty stud. also, swivel sockets are very helpful. And PB blaster (penetrating lube) works.