My oldest Sou Ry form 1014 is from 1966 (I think, undated, but newest power listed are the 1965 SD35's and the 2800 & 2900 series E6A's are still listed) and a May 6 1970 SOU form 1014 both list SOU F7A 4260 as weighing 243,520 lbs, nowhere near the heaviest among the 1951-built F7A listed; several were shown as over 244,000 lbs, so Mr. Chatfield's theory of excess weight added is disproved. SOU 4260 was listed as one of the 65/12 lower gear ratio "mountain engines" in the 1966 form 1014, but re-geared to 62/15 in the 1973 form 1014. This is the only difference shown in this source for SOU 4260.
Marvin Black related to me in the early 1970's when this box was observed on SOU 4260 that it was an attempt to reduce ambient heat that built up in the engine room during extended maximum prime mover operation. The box served as a plenum and was vented under the top lip; engine heat would rise into the chamber and motion of the locomotive would draw the heat out as it moved. It was a trial installed, photo evidence indicates, in the early 1960's. There is a May 1963 photo of 4260 leading a train with the roof modification already installed. An interesting additional observation is that all 4 36" radiator fans on this then only 12 year old 1951 built F7 were also replaced with high shroud fans, as found on early F3's. The 1971 photo of the 4260 show 2 of them still installed. I found that fan installation to be curious. Yes, I am aware that EMD 36" rooftop radiator fans are interchangeable, but to have all 4 fail and be replaced with an older version is an interesting additional anomaly. I wonder if the thinking was in some way related to the fix that was made to SOU GP7's that crews complained of inadequate cab heaters that was fixed with the large shroud applied to the radiator fan closest to the cab. Two different problems, but the approach makes me wonder whether it was coincidence or part of the trial. I have no written documentation from Marvin to confirm or deny this statement. Perhaps it is contained within Marvin's writings that the SRHA obtained from his estate.
I also was contacted by Mr. Sanders, and passed this information on to him, for what it was worth, telling him I did not have any specific reason or purpose for that modification on SOU 4260.
As far as DotSR by Withers, et.al., is concerned, the tome certainly has its errors, but I think readers and users are better served by specific and documented corrections, rather than broad brush disparagement of its accuracy. All publications are "frozen in time" after publication and flawed by the limits to updating information with better facts as they are uncovered after publication. Esteemed SOU diesel authority Marvin Black was a significant historical background and detail contributor to that volume, and his research credentials are as good as it gets. Mr. Eichelberger and those working with the SRHA archives would echo that.
One final thought: was there any collaboration with the NP on this project, either before or after? Was it suggested by an employee of SOU or NP, or a vendor, or the product of one of those RR Supplier conferences? It will be interesting to see what the SRHA archives might hold on this subject.
-----------------------------------------From: "D. Scott Chatfield"
Sent: Sunday December 1 2019 2:12:32PM
Subject: Re: [SouthernRailway] F-Unit Roof Hatches
I gave it a little more thought and I wonder if these were former roof-hung water tanks filled with concrete to add weight. I don't have an old Locomotive Summary book (my oldest is from 1975, and she was retired in 1973) so I can't look up 4260's weight. But if that box is full of concrete it should add about 10 to 11,000 pounds to the engine, assuming it extends down into the carbody about a foot. Any deeper and it would interfere with the doorway.
A normal F-unit weighed between 230,000 and 240,000 pounds. Was 4260 heavier?