You didn't say if it was an automatic or a stick shift.
A Chevy engine and Chevy transmission should line up fine (A Buick/Olds/Pontiac transmission won't fit a Chevy engine and vice versa.
Lets cover a couple scenarios that could cause problems:
If it's an automatic and you bolt the torque converter to the flex plate and try to put the transmission in that way you're in for big problems. The torque converter has 3 things that have to line up and engage in the transmission before you can bolt the transmission to the engine block -- the input shaft splines, the stator support splines, and the front pump drive lugs. You must put the torque converter on/in the transmission and turn it while pushing it into the transmission until all 3 of the above have engaged and the torque converter is all the way in. Failure to do this step right will result in catastrophe. You should be able to line up the transmission with the dowel pins on the back of the engine block and push it by hand all the way until it is seated against the block and still be able to turn the torque converter by hand when this is done properly.
If it's a stick shift the clutch disc needs to be centered with the pilot bushing in the back of the crankshaft, if it isn't you need to loosen the pressure plate and use a line up tool or an old discarded input shaft to line it up, then tighten the pressure plate to spec before putting the transmission in.
how much to replace the transmission line in 2006 Chevy impala
you can get the 2.5 liter and it should line up as long as you get the same year engine to line up on the tranmission.
no
If you are putting the same type of engine and trans it should line up however, if you are installing a V6 where a 4 cylinder came out, it won't line up.
Lift hood. Locate area between engine and transmission, look down, follow the vacuum line from the maifold to just above the starter. The unit screwed into the side of the tranny with the vacuum line coming out is the modulator.
Check for a vacuum module on the transmission. If you see a vacuum line between the transmission and engine, disconnect the line and look for transmission fluid inside the line. If you see transmission fluid in the line, replace the vacuum module. It probably has a split or damaged diaphragm inside.
If it has one it will be on the right rear of the transmission. There will be a vacuum line that attachs to it. With the engine running , parking brake set and selector in park, remove the line and see if you have engine vacuum. If not, repair the cause before replacing the valve.
automatic or manual transmission ?
The vacuum line diagram for a 1997 Chevy Venture 3.4 engine outline where each line goes and what it connects to. It can be found within the service manual.
If you are talking about the 2 steel LINE UP PINS on each side of the transmission then NO. Those two PINS should be driven into the 2 Holes that are in the back of the engine, Those holes are BIGGER then the rest of the holes.I have seen them come out and stick in the transmission bell housing but thay belong in the engine block.
On the fuel line going to the carburetor.
Clockwise