Unfortunately, retrofitting an LA360 and 1966 onward 727 into a 1957 Dodge is nothing nearly as simple as putting an LA 273/318/340/360 in a 1966 Dodge originally equipped with an A318, which is nearly a direct swap. From your location, I assume you are dealing with a domestic Dodge that was not equipped from the factory with an A-block (export Dodges in 1957 could have used an A-block depending on the model). Here's what you're into: The hemi and hemi-block poly motor mounts in your 1957 Dodge are not interchangeable with the LA mounts, so you'll have to sort those. You might be able to find a set of export A-block chassis brackets (the LA used the A-block's mounting configuration), but it'll likely be easier to fabricate or have someone fabricate your own. You'll have to address the transmission mount by either moving the 1957 crossmember or modifying it to align with the LA360/727 setup. Then there's the driveshaft. The 1957 Dodge has a ball-and-trunnion driveshaft, which I would ditch since it is an inferior design to a slip-yoke and won't be the correct length anyway. If your motorhome 727 has a parking brake drum and fixed output shaft flange like many motorhome LA360s did, you will need to have a driveline shop use the proper fixed front yoke flange on the driveshaft to mate to the 727 and then build a slip-yoke into the driveshaft. If the transmission has a slip-yoke output shaft like most post-1964 727s, you will need to have a driveshaft built with a slip-yoke flange up front. You'll need to figure out how to address the parking/emergency brake. The 1957 parking brake was on the transmission output shaft. If your motorhome 727 has the output shaft brake drum, it's as simple as figuring out how to connect the 1957 cable to the 727 cable allowing for adjustment. If the 727 does not have the brake drum, things get much more complicated since the 1957 rear end doesn't have a parking brake. In that case, I'd ditch the 1957 rear end. I used a 2001 Ford Explorer 8.8" disc brake rear end in my 1956 Dodge, or you can use a 1960's rear end with parking brake. You can read up on my 8.8" swap at https://poly318.com/1956-dodge-plymouth-ford-rear-end-swap/ The motorhome/heavy truck LA360 oil pan may not clear the 1957 Dodge crossmember and steering, so you might need to either swap in a car oil pan, use an aftermarket, or fabricate your own. You'll have to sort the shifter since the 1957 push-button can't be used with the lever-shift 727 unless you want to build a complicated and likely finicky conversion mechanism. The easiest method would be to cut a shifter hole in the floor and use a Lokar or similar floor shifter and be done with it. If you want to maintain the push button shifter, you can use a 1962 - 1965 cable-operated 727, which is what I did to install an A-block 390 stroker in my 1956 Dodge. You'll have to install a TorqueFlite A466 shifter mechanism if the 1957 Dodge has a PowerFlite, and you'll have to fabricate a parking lever to go under the dash or modify a 1962 -1 965 parking mechanism. Depending on the shifter, you might need to rewire the neutral safety switch circuit. You'll have to rewire the starter circuit since the LA360 starter incorporates the solenoid. You'll have to install an aftermarket transmission cooler and route hard lines from the 727 or use a radiator with an integral cooler. You may have clearance issues with the transmission dipstick tube and firewall depending on how far back you need to set the engine for proper radiator clearance. You can modify the factory 727 tube or use a flexible aftermarket piece. If you're using Mopar electronic ignition rather than points, you'll have to modify a later Mopar ignition switch that has an "Ignition 1" and "Ignition 2" terminal to fit in the 1957 and rewire the ignition circuit in order to properly wire the ballast resistor. I can tell you exactly how to do that to fit a 1956 Dodge dash plate, but I'm not sure if the 1957 uses the same mounting configuration. The LA360 will have a water pump with the inlet facing the right (passenger) side, whereas your 1957 radiator will have a left outlet. Simply use a 1962 - 1966 A318 water pump, which is left inlet, or use a different radiator. Depending on the 1957 Dodge steering, you might have LA360 exhaust manifold clearance issues that will require headers. You'll have to address the exhaust connection at the head pipe regardless. I think I've covered the main pitfalls but might have missed something. Of course, you'll have more minor elements such as using the 1957 water temp sending unit, rigging up accelerator and kickdown linkage/cables, radiator and heater hoses, power steering hoses if equipped, etc. | 
Engine swap
