I have been thinking and not felt sure what species they are...thats why I have not answered yet
To be honest, first I thought they could be L270 but the caudalfin seams to be to much forked...they match youngsters of L66 but the colouration dont, are they so brown and yellow or is't just the wrong colour on the pics?
If the colouration is right I would say they are L270 and also if the caudalfin when "streched" are less forked and more straight.
The Ancistrus species is not L183, there are several similar species mostly from Brasil but even some from Colombia and Peru...let it settle in and take new pics later when it has their real colour.
Janne