Try this link....
http://www.aclocogroup.co.uk/index.php
There are details and photo's of a preserved example of Class 81-85 inc.
There is also a good bibliography section containing publications that you might be able to pick up somewhere. Ebay may be a good starting place.
To tell the difference between classes, look at the ventilation grills and windows along the sides. Each class of loco has them in a different style and arrangement. In addition, the class 85 is unique among these classes by having said grills and windows set in a "depression" along both sides like an 86 or 87, rather than flush with the bodyside as on the other classes.
There are also differences with the bogies, the 82 having a noticable plate where the flexicoil springs would be on an 86/87. 84's also had oval buffers and droplight windows along the side.
I think the shape of the cab fronts is identical. I know what you mean though, when you say the 83's and 84's look a bit "chinnier" than the other's.
I think this is a visual effect with the painting of the yellow warning panels. On classes 81,82 and 85 the part of the panel that overlapped the cab side was painted vertically, ie ending in "l". On 83's and 84's the overlap was painted at an angle in a "/", which makes the cab look more protrusive at the bottom.
Hope you understand what i mean!
Regarding pantographs, i believe the standard Stone-Faiveley single arm type was standard in mainline service, two being fitted on production, one being removed to accomodate the three air resovoir cylinders whe the loco's were converted to dual air/vaccuum brakes.
In later years, certainly when restricted to ECS duties between Stonebridge Park and Euston, one or two of the 82's and 83's had the AEI cross arm pantograph fitted, as originally seen on the class 87.
Hope this helps.
hock: