Transmission Crossmembers Collect Them All!

[Gregski]

remember growing up when those silly action figure commercial would come on and they would show you like 17 of the same thing and at the end say "Collect Them All"

well that's how I am feeling lately hunting for transmission crossmembers while trying to wrap up my manual Overdrive Transmission swap on my beloved '74

but enuff about me lets take a look at the many flavors of Square Body transmission cross members (by the way is it "crossmember" one word, or "cross member" two words?)

[Gregski]

our generation starts in 1973 so it's only appropriate that our first candidates are from 1973

first let me start off by saying I know nothing about automatic transmission, I mean I know there's the 400, 350, 200, and the 700 and I think I already said too much

I mean I don't even know how to drive an automatic (that's a joke)

so check out this beauty a yellow(ish) 1973 Chayenne Super 20 (now correct me if I is wrong, but the C20 means 3/4 ton, correct? if so just keep that in the back of your head as we bring up the another truck from 1976 later on)

so this one had the transmission crossmember mounted to the bottom frame rail, we will call this crossmember a low rise as you will see later on there is one that is a bit taller (aka the high rise)

Note: this truck was an automatic, but the transmission was already gone, so we don't know what kind it had

so where am I going with this, my point is coming so just keep a readin'

[Gregski]

so here's a look at my old setup, this is a 1974 manual 4 speed the Muncie SM465

this one has a top mounted transmission crossmember

[Gregski]

ok this is where I got confused, how come this C20 aka 3/4 ton truck, also an automatic like the one from 1973 has a different transmission crossmember

yes it is still bottom mounted, however it sits about two inches higher than the one from 1973, I call it the high rise style

can you help me identify this transmission, this truck had this trans in it

[Gregski]

more / better pics of that 1976 transmission

anything on it screams TH400 or TH350?

Edit: just found this Identify My Transmission page, pretty cool, I am leaning on calling it the TH400, ha ha

[slotard]

Looking at the specs on GM Heritage Center there were all sorts of different dimensions for the frame over the years too.

[MountainGoat1966]

Keep in mind besides the various transmissions used, there were half tons, 3/4 tons, 1 tons, 2 wheel and 4 wheel drive variations, short and long wheelbase too.
That brings the possible combinations up to about a million different ones used.

[Titomars]

Originally Posted by Gregski

more / better pics of that 1976 transmission

anything on it screams TH400 or TH350?

Edit: just found this Identify My Transmission page, pretty cool, I am leaning on calling it the TH400, ha ha

That is a TH 400

the cross member from it should work nicely for your 833

[Gregski]

Originally Posted by Titomars

That is a TH 400

the cross member from it should work nicely for your 833

Thanks bud, but my money is on the TH350 crossmember, we shall find out here shortly as that is my task for this Saturday morning, gentlemen place your bets!

[Gregski]

ok, so this is yet another transmission crosssmember that I have, I believe this one came off of a mid 80s automatic 4X4

This one was also mounted on the bottom frame rail

so here it is in the original dirty condition as I pulled it off the donor truck, and then squeaky clean, and ready for paint

[Gregski]

and then I saw this one, now this one may be the whackiest of them all, I did not get this one, I sorta forgot to pull it at the Pick n Pull and I sorta didn't want it, ha ha (also it didn't look too safe to pull it - and I didn't wanna get dead)

looks like it is also an automatic crossmember here it is shown on a 1985 C10 doing what can only be described in [ahem] motorcycle terms as a "Stoppie" LOL

[Gregski]

this pic of a 1987 crossmember I borrowed from our brothers at 73-87ChevyTrucks.com should be the same as the 1985 automatic above but I just wanted to show you this beauty off the truck

[69heavychevy]

Those first two auto x-members you posted are actually the same. The first one is just missing the outer support brackets. I have only ever seen 4 different style trans x-members on these trucks.
73-79 auto, 80-87 auto, 73-79 4x4, 73+?? manual, don't quote me on it though....
Keith Seymore would probably know for sure...

[wilkin250r]

I'm just speculating, but that last goofy one you posted looks to have only one exhaust pipe headed back, I wonder if that's for the Inline 6.

[Gregski]

Originally Posted by 69heavychevy

Those first two auto x-members you posted are actually the same. The first one is just missing the outer support brackets. I have only ever seen 4 different style trans x-members on these trucks.
73-79 auto, 80-87 auto, 73-79 4x4, 73+?? manual, don't quote me on it though....
Keith Seymore would probably know for sure...

one is twice as tall as the other, the lower one came off of a TH350 truck the taller one came off of a truck with a TH400

hrere are some better comparison pics

[D13]

Trucks with catalytic converters had 'single hump' cross members. The lead pipes tied together and ran into the single converter, which was hung off a bracket at the cross member. Thus need for pipe clearance was one side only.
There seems to have been a change in the 4x4 cross members at some point, the height of the trans to t-case adapters changed.

[MikeB]

Originally Posted by Gregski

so here's a look at my old setup, this is a 1974 manual 4 speed the Muncie SM465

this one has a top mounted transmission crossmember

A question: My 82 C10 has a crossmember that's high on the drivers side for exhaust pipe clearance, but low on the passenger side. Will a crossmember like the one above fit my truck for more exhaust clearance on the passenger side? Transmission is a TH350.

[Gregski]

Originally Posted by MikeB

A question: My 82 C10 has a crossmember that's high on the drivers side for exhaust pipe clearance, but low on the passenger side. Will a crossmember like the one above fit my truck for more exhaust clearance on the passenger side? Transmission is a TH350.

I would lean towards saying yes, with the caveat that you may need to drill some new holes in it or elongate a couple, but as far as transmission position it does sit at the same height as your current cross member

but I don't know if there was a big difference in frame design between the 73-80 trucks and the 81-87 trucks so maybe someone else can comment, I always stress that they should have been broken up into two separate eras/generations but no one is listening, ha ha, jk