RCLB Frame Differences

Bdsankey

Vendor
Vendor/Sponsor
Feb 1, 2018
2,275
92
48
Neenah, Wisconsin
So I'm in process of putting together a regular cab to swap my LLY's entire driveline into. With that, I am wondering if a gas 2500 and diesel 2500hd frame are the same? IE can I go to a scrap yard and buy a gas RCLB frame and drop the duramax into the truck while being at the proper placement? Drilling holes for the trans crossmember is easy, its proper motor placement that matters to me. I have to source a frame as my RCLB roller I bought is on a cab and chassis frame which is longer, narrower, and heavier than I want for this project as I'm pretty much done sled pulling (although it's got really nice drawbar setup on it that would make another sled puller happy to buy the frame).



I ask this here because I've gotten quite a few different responses from very knowledgeable guys. The crew over at DHD says there different where the crew at TNG and the local scrap yard tell me they're the same. I just want to clarify before I go and spend money wastefully.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
17,707
226
63
Phoenix Az
if there are differences, they must be minor because i didnt see any between my old 02 and my buddies 02 8.1 when we considered doing a dmax swap in it.

if you use a 6.0 based 2500hd, the rear end will be different and trans crossmember but swapping yours over shouldnt be too much of an issue. might need to change the engine mount base plates that use the 2 through bolts in the frame. maybe something else? but cant be much
 

Bdsankey

Vendor
Vendor/Sponsor
Feb 1, 2018
2,275
92
48
Neenah, Wisconsin
if there are differences, they must be minor because i didnt see any between my old 02 and my buddies 02 8.1 when we considered doing a dmax swap in it.

if you use a 6.0 based 2500hd, the rear end will be different and trans crossmember but swapping yours over shouldnt be too much of an issue. might need to change the engine mount base plates that use the 2 through bolts in the frame. maybe something else? but cant be much
I don't necessarily care if I have to swap the base plates, my concern is that the base plate is incompatible between them where I've got to do a bunch of welding/fab work just to make it work. Trans crossmember is easy, relocating engine mounts is a job I don't want to tackle and would make me look for a diesel frame if that were the case.


I called another scrap yard and they told me GM/their system call out the same frame for gas vs diesel. He pointed out that I may have to drill for the trans crossmember and swap my axle in (already the plan) but said it shouldn't be bad but he also wasn't 100% positive.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
17,707
226
63
Phoenix Az
I don't necessarily care if I have to swap the base plates, my concern is that the base plate is incompatible between them where I've got to do a bunch of welding/fab work just to make it work. Trans crossmember is easy, relocating engine mounts is a job I don't want to tackle and would make me look for a diesel frame if that were the case.


I called another scrap yard and they told me GM/their system call out the same frame for gas vs diesel. He pointed out that I may have to drill for the trans crossmember and swap my axle in (already the plan) but said it shouldn't be bad but he also wasn't 100% positive.
thats what i mean, should just be a swap of the base plates, if even at all. I see no reason why they would make those removable and yet, move the factory holes/welded on location in the frame to accommodate the gas engine.
 

Bdsankey

Vendor
Vendor/Sponsor
Feb 1, 2018
2,275
92
48
Neenah, Wisconsin
thats what i mean, should just be a swap of the base plates, if even at all. I see no reason why they would make those removable and yet, move the factory holes/welded on location in the frame to accommodate the gas engine.
I agree with you that it would be insane to move them but who knows, it is GM we're talking about here.
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
13,664
161
63
Mid Michigan
Iirc, the front halves should be the same, minus the taller body mount horns on the HD frame. The rear under the bed on the regular 2500 should be smaller from the frame splice back....it'll be obvious to you when you see it.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
17,707
226
63
Phoenix Az
ooohhh hang on, your after the HD vs non HD frame difference? in that case, i cant offer a whole bunch but there is definitely differences. they are different like tom stated but from there, it gets dicey. It gets weird as some come with steering racks, others with drag link (2 vs 4wd), i believe the suspension geometery is different (closer to or the same asf the 1500 vs 2500hd) and you will have clearance issues with the allison and body.
 

Bdsankey

Vendor
Vendor/Sponsor
Feb 1, 2018
2,275
92
48
Neenah, Wisconsin
ooohhh hang on, your after the HD vs non HD frame difference? in that case, i cant offer a whole bunch but there is definitely differences. they are different like tom stated but from there, it gets dicey. It gets weird as some come with steering racks, others with drag link (2 vs 4wd), i believe the suspension geometery is different (closer to or the same asf the 1500 vs 2500hd) and you will have clearance issues with the allison and body.
Buddy of mine has a 01-02 2500HD door badged roller. I'll probably snag the frame/front clip and then I can have my most desirable body style while keeping my LLY running gear. I think his couple frames (he has a cateye frame and a 01-02, both door badged 2500HD) are from 4x4 6.0 gas. If you guys think that'll work I'll give it a shot.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
17,707
226
63
Phoenix Az
if you are going HD for HD, i wouldnt fret. most will be trans crossmember and rear axle difference. Torsion bars might be different too but easy swap. if you are going HD to LD, whole different ball game.
 

Bdsankey

Vendor
Vendor/Sponsor
Feb 1, 2018
2,275
92
48
Neenah, Wisconsin
if you are going HD for HD, i wouldnt fret. most will be trans crossmember and rear axle difference. Torsion bars might be different too but easy swap. if you are going HD to LD, whole different ball game.
HD to HD it is then. Guess I'm headed to Iowa one of these days once my LB7 is up and running.
 

Bbuchanan11

Member
Sep 9, 2011
122
4
18
Sarver, PA
I have a buddy that thought he bought a 2500hd 01 Silverado years ago until I pulled my lowered 06 2500hd Silverado beside it and mine sat higher. Someone put 2500hd badges and the hd front end on a 1500hd. They have a half ton frame.
 

Bbuchanan11

Member
Sep 9, 2011
122
4
18
Sarver, PA
Probably why he could never get the right parts for it. He could never get the right u joints for it and he bent the shift fork in the t case one time and the dealer said they had no listing for a auto 4wd t case option for a 2500..
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)