all v6 motors that are RWD will fit any other RWD V6 FWD blocks will not, all will use almost any v6 or sb v8 trans
While this statement is technically true, it is grossly
Its not going to be as simple as swapping any
ford v6 into your thunderbird.
There are several differences between the mustang 3.8 and the thunderbird 3.8. Mostly in sensors, but some have different timing chain covers, water pumps, accessory set ups etc. There is also a difference between the thunderbird trans and the mustang trans (most notably in shifter location)
OP your best bet is to get yourself another thunderbird/cougar engine and tranny from a similar year car and swap away. Depending on how mechanicly inclined you are, you can even swap in a 4.2 out of a F150 using the supercoupe tranny (which I believe is the same as the 3.8 lx thunderbird)
Here is some useless trivia for you:
Carbureted and FI heads are different. Carb heads have larger intake ports. FI ports are shaped similarly, but smaller. FI heads have the injectors stuck right into the head, not the intake. There is a bulge in the top of the intake port for the stream from the injector.
The roller cam from the later 3.8s ones is a billet, not a casting. Several late 3.8s have a provision for the balance shaft, but not all of them had them. As far as I know, the late model Sable/Taurus/Continental FWD 3.8s apparently had them.
There are RWD and FWD blocks. They're marked with big letters "RWD" and "FWD" on the front. The RWD blocks have the Windsor bolt pattern, but the bellhousing bolt holes are metric. They're close enough to cross-thread a 3/8" bolt into if you're not careful.
The FWD 3.8 bellhousing is the same as the 3.0 Vulcan V6 (FWD & RWD), 3.0 SHO V6, FWD 2.3, FWD 2.5HSC. You can put a FWD 3.8 V6 into a RWD application by using a RWD bellhousing from a 3.0 equipped Ranger/Explorer and a T5.
Early 3.8s had plastic valve covers. Later ones have cast aluminum valve covers.
Rod and main bearings are Cleveland size - 2.311 and 2.75. Rods are 5.95", same as a 351... or a Buick 3.8.
The cylinder head bolts are metric, close enough to 7/16". Same size as the 5.0 Ford, the 454 Chevy, or the 455 Olds. The gasket-blowing problem may be because the bolt pattern is so *wide* - the bolts are out near the water jackets instead of in near the cylinders, like on most 4-bolt cylinders.
There's a lot more unsupported head on the 3.8 (which many have attributed to the 94-94 headgasket failure problem)
It's a metric engine, but it wasn't *designed* metric. The calipers tell you it was designed in inches, then they just used metric fasteners.
The new 4.2 V6 found in the newest F150s will physically interchange with the 3.8 V6.
The crank in the 4.2 is a direct replacement for the 3.8 V6. The mains and balance are the same as the 3.8 V6. I am not sure on the deck height of the 4.2. I believe it is the same as the 3.8 as well. Just swap in the entire motor, or swap in the crank, rods and pistons and you have yourself a nice little stroker.
I will also tell you that compared to the 94-95 mustang exhaust the "log" style thunderbird exhaust manifold is restrictive as hell (might also attribute to the headgasket problem) and I would suggest sourcing a set of 3.8 mustang "shorty headers" that came stock on every 94-96 v6 mustang. Also should you chose to, you can use the newer split port design from the 99+ mustang provided you have the harness and ecu (they are great little performers and have a solid aftermarket support base) not to mention that any performace upgrade you do to a single port engine, will be much more noticable on the split port.
I hope this helps.