Driveshaft: which end goes to the transmission?

[Gregski]

sorry folks, total ignoramous here, can you please point me in the right direction so I install this spinny stick the proper way, as the Subject states, which end goes where?

please and thank you

[Gregski]

so it would appear only the short shaft mates with the transmission flange, the long shaft flange is slightly too big

[EV_Builder]

I think it won't matter. If you are gonna cut it up and reweld don't forget to rebalance it. And make sure you have everything parallel.
Especially the 2 faces of the transmission with the gearbox. So the height difference is ok but the tilt is best same angle. This keeps the joint speeds in control.

[TonyV]

Short end faces the front.

[Gregski]

I think it won't matter. If you are gonna cut it up and reweld don't forget to rebalance it.

thank you for offering to help, this is the stock OEM Lexus driveshaft that came with this Lexus GS450h transmission so I would like the proper (shorter as recently pointed out) end to mate with the transmission like from factory, that way I will only need to cut the differential end and have a professional driveshaft shop here in town (we actually have a good one, and I have been using them for years) weld on an "American" aka universal joint for me, something the likes of this

[Gregski]

since we've already mounted this horse, one more question, what should the stick out be at this center support donut where one shaft goes inside the other, on our American trucks the rule of thumb is 1" so unless I hear otherwise I'm gonna start with that

please and thank you,
g

[EV_Builder]

Just trying to help; so please don't kill me if it feels obvious

But the stick-out depends on the total allowable movement of the shaft vs the possible movement of the gearbox in both ways.

I would go with centered position. So if the shafts can move 30mm mount it at 15mm in..so it can go 15mm each way.

[Gregski]

finally got a chance to properly lay out the Chevy stick along side the Lexus one for a proper stare and compare, these are oriented in the same direction (left being the rear of the vehicle)

[Gregski]

a friend asked me to remove the rear rubber donut so here it is without it

Note: the front and rear rubber donuts are not the exact same size, the rear one is slightly larger