1971 K20 LS 5.3L Swap issue headers
 

I have installed my LS 5.3 L in to 1971 K20 4X4 truck and I'm having issue with the headers fitting Dough Throly THY 323. I talked to Dough Thorly tech prior to buying the headers to confirm that they will fit my application. they confirmed they fit. Well they don't even come close. I would like to use headers, does any one know what headers will fit. I have a Dirty Dingo motor mount installed. with 1987 bell housing with hydraulic clutch.

Re: 1971 K20 LS 5.3L Swap issue headers
 

Hooker block hugger shorties #2312

Re: 1971 K20 LS 5.3L Swap issue headers
 

Thanks for the info. would you by chance have pictures of them installed.

Re: 1971 K20 LS 5.3L Swap issue headers
 

The frame areas look minimal, I'd just clearance out the problem area. I'm not running a manual, but some "massaging" of the mounting ears on the auto's isn't uncommon.

Re: 1971 K20 LS 5.3L Swap issue headers
 

I would have to cut out the hole top flange of the frame for the right and left side. The left side the collector runs right into the hydraulic clutch bracket on the side of the bell housing.

Re: 1971 K20 LS 5.3L Swap issue headers
 

I am running DT headers and I did need to clearance the frame, just a small scallop on each side, but I reinforced the inside area, no problems so far.

Re: 1971 K20 LS 5.3L Swap issue headers
 

I checked out your build thread a couple of time it looks like your engine sits about 1 higher than mine. so the DT headers fit better. your using an auto transmission. I still have problems with the hydraulic clutch bracket that is molded in to the bell housing I would like to use.

Re: 1971 K20 LS 5.3L Swap issue headers
 

After trying 3 set of headers finally the Headman block huger headers will fit only trimming 1.4" out of the top rail of the frame on each side.

Re: 1971 K20 LS 5.3L Swap issue headers
 

So it dont matter if i buy DD or Pac fAb im still going to have trouble with headers?:smoke:

Re: 1971 K20 LS 5.3L Swap issue headers
 

That's what i found out. I ended up using the Dough Thorley headders and had to modify the 2 front tubes to clear the frame.