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TH400/NP205 crossmember ?s

88LS2K5

88LS2K5

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Swapped a 400/205 w/ short mount adapter into my 88 blazer and was wondering if the double-hump "W" shaped crossmembers and the single hump "S" crossmembers are interchangeable. And if so, are there any advantages to the double hump over the single. Thanks for any help or info. My single hump style that was pulled from the truck got sold with the 700r4 :doah:
 
same units for bolt in. only diffrence i can see is clearence for exaust to run threw . but this would put it in harms way under the crossmember.

edfit i could be wrong . i dont play with this style much at all.
 
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88LS2K5 said:
Swapped a 400/205 w/ short mount adapter into my 88 blazer and was wondering if the double-hump "W" shaped crossmembers and the single hump "S" crossmembers are interchangeable. And if so, are there any advantages to the double hump over the single. Thanks for any help or info. My single hump style that was pulled from the truck got sold with the 700r4 :doah:
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nope, only one of them will work on each truck and tranny /tcase combo.
 
Ok so votes are 1 yes and 1 no, any others? In regards to the no answer, is there a reason that the double hump wont work for me. I saw somewhere that they did use it for a 400/205 combo in something like 85 and up trucks, and also used the single hump in some of those apps. Im not too concerned about the holes in the frame not lineing up.
 
sweetk30 said:
edited my info.

iceman knows more than me on this as he has had LOTS more trucks than i :doah:
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Just so I am clear:
the crossmembers have the positions of the pad where the mount is the same location, but the W was made to clear on either side a driveshaft and or exhaust and if you put the other one in it's place the hump will interfere, and vice versa.
So if you truck need one, the other will not fit.
You need to figure out which one fits the configuration you have.
If you are building a rig and routing things the way you want, you can use either one, they will both work for the same combo.
Tomorrow when the light comes out I will take a pic of them side by side and top and bottom.
The spacing of the bolts that go on the frame are different but as you stated you can redrill to fit, so that is a non issue, one of the crossmembers is narrower in profile.
 
67-84 crossmembers are the early style, 85-91 is the "W" style. The frame widths are the same but the crossmember needs to match the adapter unless you're building your own stuff.
 
Thank you iceman for taking the time and clearing that up, I appreciate it. I should have stated in my first post that I dont think exhaust will be an issue because it will all be redone once the motor is running. The rig originally had a 700R4 in it and had the single hump crossmember. Ive had bad luck with them so I decided to go to 400/205 combo when I put the LS2 in it. Eventually I hope to put a 4L80 in place of the 400. Reason I asked about the double hump is because I came across one for sale on here. Just need to get something in there to support it and try and get this thing running again. Could always fab something but finding one for sale is easier for now.
 
The adapter I have is the short one, bolt holes for the mount are roughly 7.5" center to center. I was looking at the mount on the ORD catalog today to order one. Looks to me like the outer holes would bolt the mount to the adapter and the inner holes would bolt the mount to the crossmember. Cant remember exactly but I think the holes for the mount on the crossmember are 4.xx" center to center.
 
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