pre-units?

[scratchit]

I hope this isn't a stupid question but I keep hearing about pre-unit triumphs and bsa's but am not exactly sure what it means. Would someone take pity and educate me?!?!

[Bugles]

Pre-unit is separate motor and transmission; 'newer' Trumps are all-in-one, a 'unit', if you will.

[scratchit]

Thanks. Makes sense.

[Trumpnut]

BSA also made a semi unit . Were the trany and engine are seperate cases but bolt together .