A recent addition to the collection of operators (etc) manuals available on-line at George Elwood's marvelous "Fallen Flags"rail photo site is a General Electric "Locomotive Service Manual" for "Series-7 Road Locomotives." (It is "GEK-30150/First Edition/August, 1978" and on "Fallen Flags" as about ten PDF documents.)
The first section has general data and general appearance drawings of ... the various Dash-7 models: all NINE (or perhaps ELEVEN) of them catalogued at the time. In addition to the B23-7, B30-7, B36-7, C30-7 and C36-7 that were actually built, there is tabular data for the B18-7 (FDL-8 engine rated at 1800hp), the C23-7 (FDL-12 rated at 2250 hp: same engine as in B23-7), and the B28-7 and C28-7 (both with FDL-12 rated at 2750 hp). ((COMMENT: My recollection is that the Dash-7 line, as originally announced, had slightly less powerful "intermediates": B26-7 and C26-7. Since the FDL-12 had been tried, in some L&N U23B, at the 2750 hp rating as early as 1973, it's a little surprising that GE didn't go for the higher power from the start.))
There are five pictures (semi-diagrammatic side views) illustrating these models: one for the B18-7, and one each for the 12-cylinder BB models, the 12-cylinder CC models, the 16-cylinder BB models, and the 16-cylinder CC models. Picture captions reveal a further option: the pictures for the 16-cylinder types are labelled as representing a B33-7 and C33-7 as well as the previously noted "X30-7" and "X36-7" model pairs. ((COMMENT: I don't recall ever seeing any other indication that GE was offering a 3300 on a Dash-7 type.))
As for the appearance of the "alternate history" Dash-7s...
(1) B23-7 and B30/36-7 are both two feet longer (overall: truck spacing unchanged) than their U23B and U30/33/36B ancestors. The B18-7 shows the same two-foot stretch between the truck centers and the couplers. (The picture, but not the tabular data, suggests that the B23/28-7 would have been shorter than the 16-cylinder models: the picture was obviously obtained by literally CUTTING and pasting!)
(2) The "1966 carbody" (late U28B and U28C through end of domestic U series) types (except for the U34CH) have a central equipment blower in front of the engine, revealed on the outside by the large square air intake high on the side of the long hood between the cab and the engine compartment. The C30/36-7 has this same configuration, but four-axle Dash-7 (until the B30-7A1 for the Southern) seem to have had the central air blower at the rear: no intake vent in front of engine compartment. B18-7 would also have been like this. The C23-7 and C28-7, on the other hand, have the forward location of the central blower with the tell-tale vent. (The ventis the same distance in front of the engine as on the 16-cylinder C-7 types: the distance between the cab and the vent is longer by the equivalent of the width of two engine-compartment doors. ... The C23-7 and C28-7, in other words, look (in this respect) like the C30-7A GE finally built for Conrail in 1984.
One other oddity. The "Rotating Electrical Equipment" sectionof the manual talks about the GTA-11, but NOT about the GT-581. I think I have read elsewhere that the B18-7 was supposed to have the DC generator: either GE changed their minds about this or (more likely?) felt the likelihood of B18-7 sales was low enough that it wasn't worth wasting pages on its idiosyncracies in the general service manual for "Series-7."
The first section has general data and general appearance drawings of ... the various Dash-7 models: all NINE (or perhaps ELEVEN) of them catalogued at the time. In addition to the B23-7, B30-7, B36-7, C30-7 and C36-7 that were actually built, there is tabular data for the B18-7 (FDL-8 engine rated at 1800hp), the C23-7 (FDL-12 rated at 2250 hp: same engine as in B23-7), and the B28-7 and C28-7 (both with FDL-12 rated at 2750 hp). ((COMMENT: My recollection is that the Dash-7 line, as originally announced, had slightly less powerful "intermediates": B26-7 and C26-7. Since the FDL-12 had been tried, in some L&N U23B, at the 2750 hp rating as early as 1973, it's a little surprising that GE didn't go for the higher power from the start.))
There are five pictures (semi-diagrammatic side views) illustrating these models: one for the B18-7, and one each for the 12-cylinder BB models, the 12-cylinder CC models, the 16-cylinder BB models, and the 16-cylinder CC models. Picture captions reveal a further option: the pictures for the 16-cylinder types are labelled as representing a B33-7 and C33-7 as well as the previously noted "X30-7" and "X36-7" model pairs. ((COMMENT: I don't recall ever seeing any other indication that GE was offering a 3300 on a Dash-7 type.))
As for the appearance of the "alternate history" Dash-7s...
(1) B23-7 and B30/36-7 are both two feet longer (overall: truck spacing unchanged) than their U23B and U30/33/36B ancestors. The B18-7 shows the same two-foot stretch between the truck centers and the couplers. (The picture, but not the tabular data, suggests that the B23/28-7 would have been shorter than the 16-cylinder models: the picture was obviously obtained by literally CUTTING and pasting!)
(2) The "1966 carbody" (late U28B and U28C through end of domestic U series) types (except for the U34CH) have a central equipment blower in front of the engine, revealed on the outside by the large square air intake high on the side of the long hood between the cab and the engine compartment. The C30/36-7 has this same configuration, but four-axle Dash-7 (until the B30-7A1 for the Southern) seem to have had the central air blower at the rear: no intake vent in front of engine compartment. B18-7 would also have been like this. The C23-7 and C28-7, on the other hand, have the forward location of the central blower with the tell-tale vent. (The ventis the same distance in front of the engine as on the 16-cylinder C-7 types: the distance between the cab and the vent is longer by the equivalent of the width of two engine-compartment doors. ... The C23-7 and C28-7, in other words, look (in this respect) like the C30-7A GE finally built for Conrail in 1984.
One other oddity. The "Rotating Electrical Equipment" sectionof the manual talks about the GTA-11, but NOT about the GT-581. I think I have read elsewhere that the B18-7 was supposed to have the DC generator: either GE changed their minds about this or (more likely?) felt the likelihood of B18-7 sales was low enough that it wasn't worth wasting pages on its idiosyncracies in the general service manual for "Series-7."