One of the largest challenges for completing a Cummins conversion is obtaining the correct engine to transmission alignment. Good alignment is critical to minimizing chain coupler wear and eliminating vibrations associated with incorrectly aligned chain coupler sprockets. We have also found that the power that a chain coupler can reliably transmit without catastrophic failure is related to how well the sprockets are aligned.
In some instances, like on 2-135/155 Whites, the original engine mounting pads can be used to provide a machined surface to mount to. However, with many Oliver frames, the original mounting pads need to be removed to allow for space for the Cummins engine. For these situations, the most convenient mounting surfaces become the top of the frame and are unfortunately as-cast surfaces. Because of the variances associated with a non machined surface, mounts that simply “bolt in place” and provide automatic alignment are not practical.
The most predominant approach for Oliver conversions is to use mounts that are made of several pieces that get welded together once the engine is properly aligned. This process can be a bit tedious without the proper tools, so it's important to think through your approach before taking on a conversion. One of the best methods is to use two chain hoists with one supporting the front of the engine and the other supporting the over/under.
What also helps is to purchase a magnetic digital level. One of these levels can be set against the front face of the transmission and zeroed. When placed on a horizontal machined surface on the engine, once the level again reads zero, the engine has the proper angular alignment relative to the transmission.