Font Trouble "LT," "STD," vs. normal

Old Type 1 font files will be recognized on Mac OS as generic UNIX "exec" files, so there's actually no extension to them as they never had one (These came from pre-OS X systems which didn't use them). Soon you can't use these anyway, so it's best to move to the replacement OTF fonts. Linotype, when they upgraded to OTF versions (which Adobe first offered for sale in their Font Folios), renamed all their fonts with LT Std in the name, and there MAY have been tweaks in the metrics along the way, but the outlines are essentially identical to the existing Type 1 outlines. The "LT Std" refers to these upgraded fonts, but with no extra abilities (hence "Standard"). For the extended features, like extra Glyphs/language support/OpenType features, they also sell the LT Pro family. Either one will be the right replacement, but, yes, with the possibility of reflow initailly.

Unfortunately, Adobe no longer licenses these fonts, so going forward you do need to buy them. (Linotype/Monotype/legal resellers). Adobe DOES offer the next generation replacemt (called Trade Gothic Next), so if you're looking for a "free" option, switch everything over to that.

If you want to be consistent, you need to get everybody on the same page.

If the only difference between the two faces is kerning, you may want to try Optical Kerning instead of Metrics. Optical Kerning ignores the built in Metrics of typefaces and spaces your characters equally by comparing the relative shapes and sizes of adjacent characters and spacing the characters accordingly. You may still have problems with some missing Glyphs, but it's worth a try.

It sounds a lot like you are working in a mixed platform environment and you have a bunch of old Mac-format fonts. Changing file extensions has no bearing on what the file actually is so will have no effect.

LT at the end of the font name indicates it is from the Linotype foundry. STD indcates an OpenType font (I believe with Type 1 postscript outlines, but I'm not certain of this). Going forward you will want to use only OpenType (and OT fonts with postcript outlines are still OpenType) or TrueType fonts as Adobe is dropping support for T1 fonts. You'll want to be looking for fonts with std or pro in the name (pro fonts have larger glyph sets than std) as well as other fonts with either .ttf .otf extension(with the caveat that old Mac formt .ttf fonts are NOT cross-platform compatible).

LT stands for Linotype, which is a foundry where you will be able to purchase licences for Trade Gothic LT Std. Std stands for Standard and means that the font is an OTF font. You can also find OTF fonts with Pro in the name, instead of Std. These fonts contain more glyphes than Std fonts. OTF fonts are cross platforms and can be used on Macs and on PC's as well.

For example, one person will work on a project using the font Trade Gothic. When he is done, he will pass it on to someone else, from there the next person is unable to view that specific font and a .exec title is tagged on to the font file.

Did you try on a Mac, on a PC? It looks like it is a PostScript font (also known as Type 1). Type 1 is an old font format and is not cross platform.

We have tried to change the extension to .ttf and .otf but that also does not work.

It is completely useless. Changing a file extension will not change anything in the file. It is the same as trying to change the indd file extension by .psd or .ai