The two biggest manufacturers of Z-scale rolling stock offer outstanding freight car models. However, on Märklin models, the trucks and couplers do not look right. Micro-Trains offers freight cars in well-scaled proportion and equips them with nearly prototypical looking Magnematic couplers. Marklin produces American-style freight cars with good detailing and lettering but, with regard to couplers, they equip the cars with their standard truck-mounted type. This causes a disproportion that gives the cars a strange look. Micro-Trains offers conversion kits to change Micro-Trains models to Märklin couplers and also to change Marklin models to Micro-Trains couplers. As far as the odd look is concerned, this does not improve the Märklin models. These instructions show you how to convert Marklin models to Micro-Trains trucks and couplers, including nearly-correct scale proportions. The original trucks need to be removed. The weight in the car bottom needs to be pressed out from the bottom side. In place of the original trucks, which are set much too far in from the ends, use Micro-Trains #956 trucks and set the new bolster pin 6mm closer to the ends. Drill new 2mm diameter holes there. The bolster pin is a turned piece and must be cut, as shown on the sketch, on a lathe. For the following milling jobs, a small hobby milling machine with an adjustable tailpiece is necessary. By this machining, we remove the much-too-small and strange-looking fishbelly sides and cut clearances in the bottom for the coupler boxes of the Micro-Trains trucks. We remove the fishbelly sides with a 6mm milling cutter and for the bottom clearance, use a 1.5mm milling cutter. Paint the bolster pins black before affixing them with a two-part epoxy adhesive. Next, glue the ballast plate back in its original position and assemble the trucks with 1.4mm screws. Now have a look at your new car! Remove the bottom plate and the trucks. Drill new 2mm diameter holes for the new bolsters at a distance of 32.5mm. The new bolsters are turned parts shown on the sketch. Paint them black and fasten them with a two-part epoxy adhesive. Remove the punched sheet parts from the platforms. Fasten the Micro-Trains #905 coupler with a 1mm flat head screw and nut. Drill a 1mm hole through the platform bottom. On top, the hole must be countersunk to match the screw's flat head. This job is indeed a bit fumbly. Carefulness is not necessary since it will be covered by the punched platform bottom when reassembled. Take care to follow the right sequence when you reassemble the car. First fasten the Micro-Trains #951 trucks with the original plastic bolster pins in the new turned bolsters. Assemble the chassis to the car body. Fasten the coupler with the flat head screw and nut (if necessary remove the outer axles of the trucks for easier access). Lastly, assemble the punched platform parts. Fasten the ladder and hand rail with a small drop of CA. The Marklin tank car can also be improved in this manner. More careful work on its filigrée chassis is required. You will find instructions for this job here, later. Unfortunately the Marklin boxcar as modeled is a bit too low. There is almost no way to give this car a prototypical look at any acceptable cost