I currently have 91 Firebird with a 3.1 V6 engine.
I plan on getting a tubular k-member for my ls1/4l60e swap. What I was wondering if I would need to get a transmission crossmember as well. I have been told that the 3rd gen one will work, but I wanted to get conformation so that I am not missing anything major when the engine/trans go in. Thanks in advance.

You either need to modify the 3rd gen tranny crossmember, or buy a swap crossmember.

The LS1 4L60E mount is in a different place than all predecessors.

What needs to be done to modify the 3rd gen cross member?

Welding a new mounting point further towards the back of the car.

here's a shot of my first one:


my buddy had welded a longer than necessary tab onto mine (forgot to make all measurements before i passed it his way for welding). however, should give you a good idea what you need to do.

actually getting rid of this one too, since pocket was nice enough to include another modified one with his old y-pipe

Ok Thanks. I ended up getting the Spohn trans crossmember. What are you guys using as far as dipstick tubes? I figure the factory 4l60e dipstick wont reach, so I was thinking of getting a flexible Lokar one. What length would I need?

I have the lokar trans dipstick it is flexable so you can mountp it where ever you need to.

I went with a factory 3rd gen 700r4 dipstick & tube; wish I hadn't given mine away when I pulled the original trans, but oh well. It's a pain to get in place unless you put it in the trans before installing everything into the car

There is another option. You don't have to use the late 4L60E. Instead, the early 4L60E, like '94-'95, still mounts like the 700R-4.
It brings a different set of issues.
'94-early-'95 has no PWM, which is a good thing, but must be tuned for. Late '95 has PWM, but still installs like a 700R-4.
However, these early versions don't come with that black box at the shift stub which passes through the case. You have to do a bit of adapting there, or some more tuning.
These early 4L60Es don't have a removable bellhousing, and their tailshaft housing is the exact same as the later 700R-4, with 4 bolts, not 6.

You may regret getting the spohn crossmember later if you like having ground clearance....as for the dipstick tube I would recommend getting the lokar one as I will do that here soon because things got tight right were it comes up. But for length I would say make some measurements for yourself, although I don't think you have much choice in lengths?

For what its worth, the 700r4 3rdgen dipstick is 23 inches long. What are you guys doing to secure the top of the stock 3rd gen dipstick? Leaving it loose worm clamps?

i used a stock 3rd gen dipstick and tube and just tapped the back of my block for the mounting bracket that's on the dipstick tube

I used a 94 4L60E It uses the stock 3rdgen cross member. I also used a stock thirdgen tube and drilled out the mounting hole bigger on the tube and tapped the transmission mounting hole and used a short bolt.

I used the factory 4L60E dipstick & tube.

Not the clearest pic, but you can see the red handle/lock above the intake manifold.