gday ,just wondering if anyone knows if the 575 v8 & gearbox is identical to the dodge 300 ...(wanting to know if it will go straight into smaller truck) ...thanks

May find that the input shaft spline counts and diameters COULD be different, but other than that probably interchangeable. Early Dodge also used some NP420 boxes, some later used the NP435. As far as if you can do a straight swap with complete engine/trans as a unit, don’t they mount to the chassis differently?

i know the smaller dodges have the engine mounts on either side , not sure if the bigger trucks are the same.

I think you are asking will the motor and gearbox unit fit ......see no reason why not,unless your truck is a very early slant six......I just about sure the later 245 hemi type will take the V8 as a direct swap,because many came with the 318 in them...Simple answer is take your tape measure and check it out..........the 5 sp and 4 sp have different clutch splines ,but that is not whats asked..

Actually, there's a good point there. Trucksyd was referring to the AT4 series.
Just which years did that cover?
Got a couple of AT series Dodges kicking around in paddocks around here as well as later series, some seem to have the 420 box others the 435, some seem to have the centre mounted transverse front crossmember, others the side hung type (a la Valiant V8).
Couple of variations on the rear xmember as well, some hung off the bellhousing, some on the xmember itself. May depend on just which year manufactured?
I know firsthand that locating the exact replacement mounting rubbers can be a bit of a bitch if you are using later model boxes in earlier series, or other applications.
Either way, I would have thought that the blocks themselves would have been drilled and tapped to accomodate either type of mount, although I have some strange idea that the truck V8 318's were a different casting from the normal Valiant V8 blocks.
But, as usual IDSTBC

the truck 318s are quite different from the car ones .........but on the subject of 318s ,there are at least 5 different kinds of 318,and all the differences will do your head in....I f you are interested ,I can put you in touch with a guy who will get all worked up about the subject ,and start punching posts ,and foaming at the mouth about Chrysler Australia being sold to Mitsubishi......not to mention about what exactly a "Burma Dodge " is.....best not to ask.

Yes ,mine is a d5n 300, 245hemi , the reason I want to swap is it feels underpowered & slow off the mark.i think it pumps out 140hp .The 318 I believe has another 40 hp . I will do some measuring & see how I go.

Don't the truck 318 engines fall into being classed as an industrial engine and hence the differences?

I’m sure you would have thought about tail shaft lengths will be different than the 245 maybe be longer than 318 and different rear extension
Shafts maybe different for the lighter duty and heavier duty box
And the last thing is the little truck more than likely has a smaller uni ....
Do the tape measure thing before you start.
just trying to save you from a headache, your probably a step a head anyway Jim

Splicing tailshafts is simple.Done hundreds.......Ive even made up mismatched unis for Dodge Inter parts swaps.......would have caused some head scratching when replacement time came.......used to get a lot of the fire trucks that had a pump drive box in the driveline,and for some reason whoever fitted the pumps /drives always used weird unis.....still got some of the Chelsea drive boxes.