ZF S5-20 question

[FJ60]

Is there a difference in the ZF S5-20 used by Mercedes and Maserati? 
I found a ZF S5-20 that came out of a late 1960's Ghibli (I believe) that I was planning to have installed in a W113. 
This ZF looks the same as the ZF shown in the rebuild manual (REF-247) but is much longer than a Mercedes 4 speed tranny.  It also looks different from the picture of the new  ZF S5-20 that I have seen on the web.  It looks like part 803 speedometer cover is different.
My mechanic said that this ZF will not fit my W113 without reworking the tunnel.
Any thoughts??

[FJ60]

Looking thru the ZF S5-20 assembly guide, I think I found my answer.  It appears there is a "short" and "long" of the ZF S5-20 and that the W113 used the short version and the Maserati used the long version. The difference is in the speedmeter cover, the power block and shorter gear shift. These are graphically shown in Figure 16-1 and 16-1/a of REF 247.. 

Am I correct?

If so, is there a source for parts to convert this tranny to work in a W113?

[mbzse]

../...ZF S5-20.../...the W113 used the short version and the Maserati used the long version. The difference is.../...Am I correct?

Well, partly. Many more differences. Really, only the internals are corresponding between M-B and Maserati versions. For instance, housing is alloy on Maserati, cast steel on M-B.
/Hans S